Remember the mammoths, say the clean-cut organisers at the youth camp's mass wedding. "They became extinct because they did not have enough sex. That must not happen to Russia".

Obediently, couples move to a special section of dormitory tents arranged in a heart-shape and called the Love Oasis, where they can start procreating for the motherland.

With its relentlessly upbeat tone, bizarre ideas and tight control, it sounds like a weird indoctrination session for a phoney religious cult.

But this organisation - known as "Nashi", meaning "Ours" - is youth movement run by Vladimir Putin's Kremlin that has become a central part of Russian political life.

Nashi's annual camp, 200 miles outside Moscow, is attended by 10,000 uniformed youngsters and involves two weeks of lectures and physical fitness.

Attendance is monitored via compulsory electronic badges and anyone who misses three events is expelled. So are drinkers; alcohol is banned. But sex is encouraged, and condoms are nowhere on sale.

Bizarrely, young women are encouraged to hand in thongs and other skimpy underwear - supposedly a cause of sterility - and given more wholesome and substantial undergarments.

Twenty-five couples marry at the start of the camp's first week and ten more at the start of the second. These mass weddings, the ultimate expression of devotion to the motherland, are legal and conducted by a civil official.

Attempting to raise Russia's dismally low birthrate even by eccentric-seeming means might be understandable. Certainly, the country's demographic outlook is dire. The hard-drinking, hardsmoking and disease-ridden population is set to plunge by a million a year in the next decade.

But the real aim of the youth camp - and the 100,000-strong movement behind it - is not to improve Russia's demographic profile, but to attack democracy.

Under Mr Putin, Russia is sliding into fascism, with state control of the economy, media, politics and society becoming increasingly heavy-handed. And Nashi, along with other similar youth movements, such as 'Young Guard', and 'Young Russia', is in the forefront of the charge.

At the start, it was all too easy to mock. I attended an early event run by its predecessor, 'Walking together', in the heart of Moscow in 2000. A motley collection of youngsters were collecting 'unpatriotic' works of fiction for destruction.

It was sinister in theory, recalling the Nazis' book-burning in the 1930s, but it was laughable in practice. There was no sign of ordinary members of the public handing in books (the copies piled on the pavement had been brought by the organisers).

Once the television cameras had left, the event organisers admitted that they were not really volunteers, but being paid by "sponsors". The idea that Russia's anarchic, apathetic youth would ever be attracted into a disciplined mass movement in support of their president - what critics called a "Putinjugend", recalling the "Hitlerjugend" (German for "Hitler Youth") - seemed fanciful.

How wrong we were. Life for young people in Russia without connections is a mixture of inadequate and corrupt education, and a choice of boring dead-end jobs. Like the Hitler Youth and the Soviet Union's Young Pioneers, Nashi and its allied movements offer not just excitement, friendship and a sense of purpose - but a leg up in life, too.

Nashi's senior officials - known, in an eerie echo of the Soviet era, as "Commissars" - get free places at top universities. Thereafter, they can expect good jobs in politics or business - which in Russia nowadays, under the Kremlin's crony capitalism, are increasingly the same thing.

Nashi and similar outfits are the Kremlin's first line of defence against its greatest fear: real democracy. Like the sheep chanting "Four legs good, two legs bad" in George Orwell's Animal Farm, they can intimidate through noise and numbers.

Nashi supporters drown out protests by Russia's feeble and divided democratic opposition and use violence to drive them off the streets.

The group's leaders insist that the only connection to officialdom is loyalty to the president. If so, they seem remarkably well-informed.

In July 2006, the British ambassador, Sir Anthony Brenton, infuriated the Kremlin by attending an opposition meeting. For months afterwards, he was noisily harassed by groups of Nashi supporters demanding that he "apologise". With uncanny accuracy, the hooligans knew his movements in advance - a sign of official tip-offs.

Even when Nashi flagrantly breaks the law, the authorities do not intervene. After Estonia enraged Russia by moving a Sovietera war memorial in April, Nashi led the blockade of Estonia's Moscow embassy. It daubed the building with graffiti, blasted it with Stalinera military music, ripped down the Estonian flag and attacked a visiting ambassador's car. The Moscow police, who normally stamp ruthlessly on public protest, stood by.

Nashi fits perfectly into the Kremlin's newly-minted ideology of "Sovereign democracy". This is not the mind-numbing jargon of Marxism-Leninism, but a lightweight collection of cliches and slogans promoting Russia's supposed unique political and spiritual culture.

It is strongly reminiscent of the Tsarist era slogan: "Autocracy, Orthodoxy and Nationality".

The similarities to both the Soviet and Tsarist eras are striking. Communist ideologues once spent much of their time explaining why their party deserved its monopoly of power, even though the promised utopia seemed indefinitely delayed.

Today, the Kremlin's ideology chief Vladislav Surkov is trying to explain why questioning the crooks and spooks who run Russia is not just mistaken, but treacherous.

Yet, by comparison with other outfits, Nashi looks relatively civilised. Its racism and prejudice is implied, but not trumpeted. Other pro-Kremlin youth groups are hounding gays and foreigners off the streets of Moscow. Mestnye [The Locals] recently distributed leaflets urging Muscovites to boycott non-Russian cab drivers.

These showed a young blonde Russian refusing a ride from a swarthy, beetle-browed taxi driver, under the slogan: "We're not going the same way."

Such unofficial xenophobia matches the official stance. On April 1, a decree explicitly backed by Mr Putin banned foreigners from trading in Russia's retail markets. By some estimates, 12m people are working illegally in Russia.

Those who hoped that Russia's first post-totalitarian generation would be liberal, have been dissapointed. Although explicit support for extremist and racist groups is in the low single figures, support for racist sentiments is mushrooming.

Slogans such as "Russia for the Russians" now attract the support of half of the population. Echoing Kremlin propaganda, Nashi denounced Estonians as "fascist", for daring to say that they find Nazi and Soviet memorials equally repugnant. But, in truth, it is in Russia that fascism is all too evident.

The Kremlin sees no role for a democratic opposition, denouncing its leaders as stooges and traitors. Sadly, most Russians agree: a recent poll showed that a majority believed that opposition parties should not be allowed to take power.

Just as the Nazis in 1930s rewrote Germany's history, the Putin Kremlin is rewriting Russia's. It has rehaabilitated Stalin, the greatest massmurderer of the 20th century. And it is demonising Boris Yeltsin, Russia's first democratically-elected president. That he destroyed totalitarianism is ignored. Instead, he is denounced for his "weak" pro-Western policies.

While distorting its own history, the Kremlin denounces other countries. Mr Putin was quick to blame Britain's "colonial mentality" for our government's request that Russia try to find a legal means of extraditing Andrei Lugovoi, the prime suspect in the murder of Alexander Litvinenko.

Yet the truth is that Britain, like most Western countries, flagellates itself for the crimes of the past. Indeed, British schoolchildren rarely learn anything positive about their country's empire. And, if Mr Putin has his way, Russian pupils will learn nothing bad about the Soviet empire, which was far bloodier, more brutal - and more recent.

A new guide for history teachers - explicitly endorsed by Mr Putin - brushes off Stalin's crimes. It describes him as "the most successful leader of the USSR". But it skates over the colossal human cost - 25m people were shot and starved in the cause of communism.

"Political repression was used to mobilise not only rank-and-file citizens but also the ruling elite," it says. In other words, Stalin wanted to make the country strong, so he may have been a bit harsh at times. At any time since the collapse of Soviet totalitarianism in the late 1980s, that would have seemed a nauseating whitewash. Now, it is treated as bald historical fact.

If Stalin made mistakes, so what? Lots of people make mistakes.

"Problematic pages in our history exist," Mr Putin said last week. But: "we have less than some countries. And ours are not as terrible as those of some others." He compared the Great Terror of 1937, when 700,000 people were murdered in a purge by Stalin's secret police, to the atom bomb on Hiroshima.

The comparison is preposterous. A strong argument can be made that by ending the war quickly, the atom bombs saved countless lives.

Franklin D Roosevelt and Harry Truman-may have failed to realise that nuclear weapons would one day endanger humanity's survival. But, unlike Stalin, they were not genocidal maniacs.

As the new cold war deepens, Mr Putin echoes, consciously or unconsciously, the favourite weapon of Soviet propagandists in the last one.

Asked about Afghanistan, they would cite Vietnam. Castigated for the plight of Soviet Jews, they would complain with treacly sincerity about discrimination against American blacks. Every blot on the Soviet record was matched by something, real or imagined, that the West had done.

But the contrasts even then were absurd. When the American administration blundered into Vietnam, hundreds of thousands of people protested in the heart of Washington. When eight extraordinarily brave Soviet dissidents tried to demonstrate in Red Square against the invasion of Czechoslovakia, in 1968, they were instantly arrested and spent many years in labour camps.

For the east European countries with first-hand experience of Stalinist terror, the Kremlin's rewriting of history could hardly be more scary. Not only does Russia see no reason to apologise for their suffering under Kremlin rule, it now sees the collapse of communism not as a time of liberation, but as an era of pitiable weakness.

Russia barely commemorates even the damage it did to itself, let alone the appalling suffering inflicted on other people. Nashi is both a symptom of the way Russia is going - and a means of entrenching the drift to fascism.

Terrifyingly, the revived Soviet view of history is now widely held in Russia. A poll this week of Russian teenagers showed that a majority believe that Stalin did more good things than bad.

If tens of thousands of uniformed German youngsters were marching across Germany in support of an authoritarian Fuhrer, baiting foreigners and praising Hitler, alarm bells would be jangling all across Europe. So why aren't they ringing about Nashi?