Moscow (AFP) - Russian police blocked the Moscow campaign office of top opposition politician Alexei Navalny on Thursday on the eve of his scheduled release from a 25-day jail term, campaign staff said.
"Unknown individuals broke into our office in the night," campaign team member Nikolai Lyaskin told AFP.
"They sawed through the locks and put up metal bars everywhere."
He added a dozen of policemen were near the building and several more were inside in plainsclothes.
Nobody there was answering any questions about the reasons for their presence, he said.
An AFP photographer observed several police and at least one police car near the premises, which activists and supporters were not allowed to enter.
Navalny campaigner Vitaly Serukanov said on Twitter that the policemen seized computers and campaign materials.
On Thursday, Navalny's campaigners reported police blocking a similar office in Siberian city Novosibirsk, where two activists were briefly detained and charged with resisting police.
Navalny has announced his intention to run for president in the next year's elections, emerging as Russia's most prominent opposition leader.
He has already called two massive protests this year.
He was arrested on his way to the latest protest on June 12, while still in the stairwell of his apartment building, and swiftly sentenced to 25 days in police cells, a sentence that expires Friday.
He was previously given 15 days of arrest on March 26, the date of the first protest against corruption in the government, which saw thousands of people flood central Moscow despite lack of rally authorisation.
His political future however remains unclear as Navalny has been convicted of fraud in 2013.
He and his supporters have faced constant attacks. Navalny was forced to seek medical attention abroad after his eye was burned by medical ointment thrown in his face.