Some 2,000 people today crammed into a Moscow square amid a heavy police presence for a banned rock concert to protest plans to build a motorway through a forest outside the Russian capital.
The numbers were far higher than for past opposition rallies in Moscow but the concert failed to get off the ground after police refused to allow amplification gear through tight security, an AFP correspondent at the scene reported.
However, veteran rocker Yuri Shevchuk, who opposed the Soviet regime and now the government of Prime Minister Vladimir Putin, pleased his fans by climbing onto a stepladder and singing some well-loved songs without a microphone.
Dozens of police vehicles and members of the feared OMON anti-riot police, equipped with helmets and bullet-proof vests, thronged the square.
The concert's aim was to buttress efforts by environmental activists to oppose the construction of a highway through Khimki forest outside Moscow, which has become a symbol for Russians fighting for their rights.
While the demonstration on Pushkin Square against the construction of the road had been sanctioned by the Moscow authorities, they had explicitly banned the holding of a concert.
"We came to make beautiful speeches and sing beautiful songs. But we have a problem," Artemi Troitski, one of the organisers, said.
"The sound equipment is in the car over there and the security forces are not allowing it to come on the square."
Several opposition activists were detained ahead of the rally, including prominent campaigner Lev Ponomaryov, officials said.
Another 20 activists, including Mikhail Shneider of opposition movement Solidarnost and ex-government minister Boris Nemtsov, were also detained in an earlier protest as they tried to carry a Russian flag in central Moscow to celebrate the official Flag Day holiday.
"The problem is that -- for one reason or another -- the authorities are scared of people with guitars," Shevchuk said as he arrived for the rally, clutching his guitar.
The Khimki forest northwest of Moscow is a "symbol of the civic struggle against the arbitrariness of the state," he added.
Shevchuk in May had openly challenged Putin telling him at a face-to-face meeting that Russia was being ruled by "dukes and princes with sirens on their cars" and demonstrations are broken up by "repressive" security services.