Communist Party lawyer Maksim Sikach told Novaya Gazeta that the police arrived at the building in downtown Moscow on September 28, a few minutes before the Communists were going to leave to register documents in court. Sikach said the lawsuit has to be filed no later than September 29.

"We had been preparing a claim against [the results of] remote electronic voting for 10 days. We were all this time in our office writing the claim," Sikach said. According to him, five minutes before they were about to leave to file the lawsuit, police officers came and blocked the entrances of the building.

During the September 17-19 election, in several regions including Moscow, people were able to cast votes online for the first time for the State Duma -- Russia's lower house of parliament.

Because the results of the e-voting were published late and influenced the final result in favor of United Russia, the opposition Communist Party, which came a distant second in the polls with just under 19 percent, accused the authorities of fraud, with party leader Gennady Zyuganov announcing that all Moscow party candidates intended to sue.

After the vote, the independent election-monitoring group Golos said 78,000 more electronic ballots had appeared in the officials' Moscow tally than were issued, highlighting what it called the "shame" of "one of the dirtiest" elections in Russian history and calling for the electronic votes to be nullified.

Two protests, attended by several hundred, mainly Communist, sympathizers were staged in Moscow on September 19 and 25, with participants claiming they were cheated of victory by the online voting system and calling for the system to be scrapped.

Sikach said on September 28 that the police demanded to be allowed into the building but the Communists refused to let them in.

"Our premises are under siege. We understand that their goal is to detain us. We have all the documents, the candidates are waiting for us at the court," the lawyer explained.

Russia's Ministry of Internal Affairs has not yet commented on the incident.