The Communist Party has sent a request to several government agencies to check United Russia's financing for possible foreign donors.
The request, sent to the Prosecutor General's office, the Federal Tax Service, the Central Elections Commission and the Justice Ministry, was based on information that some money for the majority party's support fund had come from abroad, Interfax reported.
Communist lawyer Vadim Solovyov demanded that United Russia end illegal financing and give money received from foreign sources back to the contributors or to the state budget.
Solovyov also pointed out that if the suspicions are correct the Justice Ministry may issue a warning to the party and refer the case to the Supreme Court. In case of repeated violations the latter may suspend the United Russia's activity or ban it altogether, the lawyer noted.
Konstantin Mazurevsky, deputy head of United Russia's executive committee, said Friday that his party has not received any warnings from regulators concerning its financing, which strictly adheres to current legislation.
The party's press office also released a statement from deputy head of the Central Elections Commission Leonid Ivlev, who confirmed the absence of any complaints.
The Prosecutor General's office is investigating an earlier accusation from Liberal Democratic Party leader Vladimir Zhirinovsky that Alexei Navalny's mayoral campaign might be financed from abroad.
On Monday, prosecutors claimed more than 300 foreign individuals and organizations from the U.S., Britain, Finland, Canada and Switzerland may have transferred money to Navalny's supporters using Yandex accounts.