Navalny's spokeswoman Kira Yarmish reported on Twitter that Navalny and at least one of his associates had been apprehended, which was confirmed by the Moscow police later on Sunday.

According to a police spokesperson, the pair was detained "for attempting to cause a public disturbance."

Roman Rubanov, the director of Navalny's anti-corruption foundation, also tweeted about being detained, although that information has not yet been confirmed.

Navalny and his supporters were distributing leaflets urging people to participate in an "anti-crisis" march, set for March 1. Russia is facing a deep economic crisis following the slump in oil prices and sanctions over the conflict in Ukraine.

Yarmish also tweeted that supporters have continued to distribute opposition material despite the police involvement.

Navalny, a popular blogger and one-time candidate for Moscow mayor, was convicted of fraud in December and given a suspended sentence. The critic of President Vladimir Putin was then ordered to remain under house arrest until his appeals were exhausted.

But Navalny has said he would not follow the court's orders and has left his home several times since then, according to Russian media.

Also in December, Navalny's brother Oleg was sentenced to three-and-a-half years in prison.

dj/cmk (AP, Interfax)