The search by a dozen police ended about 1 am. It was not immediately clear if the police took away items as potential evidence, but photos posted by Navalny's staff on social media showed them bagging material including a coffee mug.

There was no statement from police about the reason for the search; the Mediazona news website that focuses on political repressions and human rights abuses cited a Navalny staff member as saying that police said they had received a report that pornography was being published at the office.

Navalny was arrested on January 17 when he returned to Russia from Germany, where he had spent five months recovering from nerve-agent poisoning that he blames on the Kremlin.

He later was ordered to serve 2 1/2 years in prison on the grounds that his time in Germany violated a suspended sentence he was handed in a money-laundering and fraud conviction.