MOSCOW, December 17 - RAPSI. The police released all individuals detained on Saturday during an unauthorized rally in central Moscow, including whistleblowing lawyer Alexei Navalny, leftist opposition figure Sergei Udaltsov, liberal politician Ilya Yashin and socialite-turned-political activist Ksenia Sobchak, the Interior Ministry's press service told RIA Novosti.

All were released after protocols on administrative offences were drafted, according to the press service.

Activists headed to downtown Lubyanka Square to mark the first anniversary of large-scale opposition protests in Russia by laying flowers at a memorial to victims of political persecution in the Soviet Union.

The rally was not sanctioned by City Hall, giving police the right to detain people in the square.

Udaltsov was detained as he was giving a speech by the memorial; Yashin and Sobchak were stopped as they were approaching the square and Navalny after he gave a speech at the event. The three were reportedly taken to a nearby police precinct.

The police said that they had been detained for calling people to stage an unsanctioned rally.

A number of other opposition politicians, including Boris Nemtsov and Ilya Ponomaryov, were able to address the crowd by the memorial unhindered by police.

The police reported that around 700 people took part in the unauthorized rally at Lubyanka Square. Around 40 individuals were detained for unlawful actions.

Rallies also took place in several other Russian cities, including Voronezh, Yaroslavl and St. Petersburg, although these had been sanctioned.