Russian authorities warned today that they will clamp down on an unsanctioned gay rights parade in Moscow that has been called to coincide with tomorrow's annual extravaganza of kitsch, the Eurovision Song Contest final.

Russia has promoted the contest as the latest example of its ability to host large-scale international events.

But away from the lights and the laser beams at the 80,000-capacity Olympiysk Arena – where acts from 25 nations will battle it out for the Eurovision crown, including Jade Ewen from Britain – the Slavic Gay Pride parade in central Moscow risks producing clashes between activists, police and extreme rightwingers.

Previous attempts to hold a gay rights parade in Moscow were banned by the city and activists who defied the bans and showed up were violently harassed by ultra-nationalists.

“In case any sort of unsanctioned actions are carried out, whether it be the gay parade or some other event, the police will act strictly in adherence with the law,” said Leonid Vedenov, a police major-general who heads the public safety department of the Russian Interior Ministry.

Organisers of the parade said that they would still hold the event at 0900 GMT in Pushkin Square. “We have decided to stand up for our right to freedom of assembly,” they said in a statement.

Homosexuality was a crime in Russia until 1993 and was classified as a mental illness until 1999. The Moscow city government on Tuesday blocked an attempt by two lesbians to get married on the eve of the Song Contest.

Peter Tatchell, the prominent British gay rights campaigner who was beaten up on a gay march in Moscow two years ago, plans to attend tomorrow's parade. “Although I am determined to support our Russian comrades, like them I am anxious about what may happen to us," he said in a statement this week.

Eurovision is the latest large event to be held in Russia under the leadership of Vladimir Putin. The country hosted the football Champions League Final last year and is due to host the 2014 Winter Olympics.

Moscow has been festooned with Eurovision banners in the white, blue and red of the Russian flag and pictures of Ksenya Sukhinova, Russia's reigning Miss World, voluptuously dressed in the national colours of all the entrants.

Norway is the bookies’ favourite to win the contest from the 25 acts, with an entry that appears aimed at breaking recent Eastern European domination of the contest by beating them at their own game.

The song, Fairytale, is sung by the Belarus-born Alexander Rybak and features an Eastern European-style rhythm and Cossack dancing.

Also high in the running are the oriental rhythms and belly dancing of Düm Tek Tek from Hadise of Turkey and the disco beat of This is Our Night from the heart-throb Greek superstar Sakis Rouvas.

Hopes were rising for Jade Ewen, the British contestant, today as she puts the final preparations to her attempt to revive the UK’s fortunes. The 21-year-old singer-actress will be hoping to fare better than last year's entrant, Andy Abraham, who finished joint last, raising questions about whether there was any point in the UK bothering to enter the competition if political voting took precedence.

Graham Norton will take on the commentating duties for the first time after his predecessor, Sir Terry Wogan, who has been associated with the competition from the early 1970s, said after Abraham’s disappointment that it was “no longer a music contest” and that prospects for Western European participants were poor.

“It did get to Terry in the end, but he’d been doing it for 35 years, so it probably won’t annoy me quite as much,” Norton told the BBC.

“It’s frustrating because it does take the fun out of it.

"The voting sequence should be very exciting, but if you know who everyone is going to vote for then it’s less exciting.”

He said that he would not imitate Sir Terry and would poke fun only if it was worth it. He added: “Listening to the songs, I think a lot of them are actually quite good this year.”

Russia, Serbia and Ukraine have all won in recent years, helped by a tendency for viewers in former Communist states to vote as a bloc in the televoting that decided the contest.

However this time organisers have responded to criticism of bloc voting by introducing a new system that gives professional juries half of the vote and viewers from across Europe the other half.

Western European countries have also brought out some heavy weaponry to break the Eastern and Scandinavian dominance of the contest. Ewen will be singing It’s My Time, written by Andrew Lloyd Webber, while France is fielding the pop diva Patricia Kaas.

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