Gay rights activist Peter Tatchell and singer Richard Fairbrass have expressed their shock after being punched by anti-homosexual protesters in Moscow.
Both men were hit on the head during a gay rights march on Sunday. Protesters attacked with kicks, punches and eggs.
Mr Tatchell, Mr Fairbrass and two European Parliament deputies were among 31 people detained by Russian police.
London Mayor Ken Livingstone deplored the violence, as did the mayors of Paris and Rome.
The gay rights demonstrators were trying to deliver a petition to Moscow Mayor Yuri Luzhkov, demanding the right to stage public marches.
Attackers 'walked free'
Speaking to Sky News, Mr Tatchell said "We were violently assaulted - I was battered in the face and the eye, and knocked to the ground, kicked and beaten".
"The Moscow police, astonishingly, arrested me and let my attackers walk free," he said.
Fairbrass: "I actually felt more sorry for the guy that whacked me"
Richard Fairbrass, a singer with the band Right Said Fred, told BBC Radio Five Live that he would be travelling with security in Eastern Europe from now on.
"We've never travelled with security in Moscow, Latvia, any of the old eastern bloc countries, but I have to say I wouldn't... travel now without having our own security guys with us, no," he said.
"When it was over I actually felt more sorry for the guy that whacked me than I did for me... How threatened can he be, how insecure is he to be threatened by a bisexual pop singer who's most famous for singing 'I'm too sexy'?"
Italian MEP Marco Cappato was kicked by an anti-gay rights protester and then arrested when he demanded police protection.
Another MEP, Volker Beck from Germany, was also detained, along with the leader of GayRussia, Nikolai Alexeyev.
Mayor Livingstone wrote to Moscow's Mayor Luzhkov voicing "deep concern" and urged him to get all charges against Mr Tatchell and fellow demonstrators lifted. He also urged Mr Luzhkov to lift the ban on the Gay Pride parade in Moscow.
Mr Luzhkov has called homosexuality "satanic" and says he will never allow gay rights parades in Russia's capital.
The counter-demonstration was staged by ultra-nationalists and members of the Russian Orthodox Church. Some of them chanted "Moscow is not Sodom!"
Sunday's march was to commemorate the 14th anniversary of the decriminalisation of homosexuality in Russia.
Paris Mayor Bertrand Delanoe condemned Sunday's "unacceptable violence," while Rome Mayor Walter Veltroni said the "sad" incident in Moscow "leaves you speechless".
Moscow city police spokesman Viktor Bryukov had warned the organisers not to go ahead.
Gay activists were also attacked by right-wing protesters and arrested during a march last year.
The head of the Russian Orthodox Church, Patriarch Alexy II, supports the ban on gay parades.