Irish super group U2's first Russia concert was marred Thursday after police detained rights campaigners at the jam-packed venue and tore down tents to prevent them gathering signatures for petitions.
Some 75,000 fans flocked to Wednesday evening's showpiece in a Moscow stadium which came the day after U2 frontman Bono held talks with rock-loving President Dmitry Medvedev on issues including preventing the spread of polio and HIV.
Bono praised Medvedev as "gracious" in front of the crowd but also as a finale invited Russian rock star Yury Shevchuk - famous for his outbursts against the Kremlin - to the stage for a duet.
Police not only forced out activists handing out leaflets and gathering signatures but also U2's own charity fund, the ONE Campaign against AIDS, activists said on Thursday.
"The tents of Amnesty International, Greenpeace and the ONE foundation were removed by police and we were not allowed to collect signatures and to talk to people," Greenpeace Russian director Ivan Blokov said.
"Our activities were agreed with U2's management, so we are very much surprised," he told AFP.
Moscow police however said the concert was not the moment to mix music and politics. "All of that held the unquestionable trappings of an unsanctioned picket," the Interfax news agency quoted a police spokesman as saying.
Amnesty International's Russia head told AFP that five of the rights watchdog's activists were detained ahead of Wednesday's concert.
"It is sad that in Russia - which is considered a civilised country - the collection of petition signatures so worries the authorities," Sergei Nikitin said.
"You get the impression that the authorities are afraid of their own citizens."
He protested that Amnesty had carried out similar awareness work with U2's encouragement throughout the band's European tour and that two of its activists had in fact travelled with U2 from the United States.
"I don't know if Bono knows about what happened to us," he said. He noted that the frontman was one of the organisation's chief activists.
"It was a typical publicity event, which this organisation has carried out in every city where U2 has performed," he said.
For the show's finale, Bono invited Soviet-era rock star turned anti-Kremlin activist Shevchuk onstage for a rendition of the Bob Dylan classic Knockin' on Heaven's Door, hailing the veteran Russian singer as a "great man."
"What a time we've had in this extraordinary city of yours," Bono was quoted on U2's website as saying during the concert. "An amazing singer, Yury Shevchuk, is with us tonight. What a great man!"
Prominent Russian rock critic Artemi Troitsky told the RIA Novosti news agency that the idea of the duet had been agreed an hour before concert, with the monolingual Shevchuk helped by a crib sheet of the song's lyrics.
"It was quite a task for Yury, given that he does not know English well and he has never had to sing in English," he said.
Shevchuk on Sunday had appeared in front of some 2,000 people for a banned concert in central Moscow protesting plans to build a motorway through a forest, when he was forced by the security forces to sing without any amplification.
To the fury of activists, leading rights campaigner and Kremlin critic Lev Ponomaryov was jailed for three days by a Russian court Wednesday for taking part in Sunday's demonstration.
The 68-year-old activist's daughter told Interfax on Thursday that doctors were worried over Ponomaryov's health in detention as the veteran campaigner suffered from high blood pressure.