Russian protest leader Navalny briefly detained

Russian police briefly detained opposition politician Alexei Navalny Wednesday after he formally filed his candidacy for the September mayoral elections in Moscow.

Navalny, who has mobilised supporters to campaign ahead of the snap polls even though he faces a jail term in an embezzlement trial, arrived at the building of the election commission where he was greeted by about 200 people who shouted "Navalny is our mayor!".

"Your actions are illegal!" the police told the crowd as Navalny began to address people, including many journalists. Officers then surrounded the lawyer and took him away to the detention minibus.

He was released shortly after, when the crowd surrounded the bus and prevented it from driving off.

Navalny faces up to six years in jail in the embezzlement trial held 900 kilometres away from the capital in Kirov. The verdict will be announced on July 18.

If his candidacy is accepted, Navalny will face the incumbent Sergei Sobyanin, who was appointed by Vladimir Putin in 2010, in the polls.

Sobyanin is campaigning as an independent candidate after quitting his post last month, in what is seen by critics as an apparent bid to outmanoeuvre the opposition.

A poll published Wednesday by independent Levada centre showed Sobyanin far ahead of Navalny, with 78 percent of those surveyed saying they will vote for the incumbent mayor, while only eight percent said they will vote for Navalny.