Russian authorities have filed a legal case against an election watchdog, accusing it of failing to declare itself a "foreign agent".
The group, Golos, is the first non-governmental organisation targeted under a new law requiring such groups that receive financial aid from abroad to register as foreign agents.
The law was passed after mass protests against President Vladimir Putin.
Golos said it would fight to prove its innocence.
In recent weeks, more than 100 civil society and human rights groups across Russia have been subjected to inspections by prosecutors and tax officials in connection with the law.
Now Golos - one of the country's most prominent NGOs, whose name means both "voice" and "vote" - has been accused by the Justice Ministry of being an unregistered "foreign agent".
The case is to be presented to a court on Wednesday. The group could be fined up to 500,000 roubles ($16,000; £10,500) and its director up to 300,000 roubles.
But on Tuesday, director Liliya Shibanova told state news agency RIA Novosti that the group had not received foreign funding since the law took effect.
"I don't know on what basis they're doing this," she said.
Golos collected and published evidence of alleged fraud in Russia's parliamentary poll just over a year ago, says the BBC's Steve Rosenberg in Moscow.
Those claims of vote-rigging in favour of the party in power sparked mass protests in Moscow and other major cities.
The Russian authorities were furious and accused NGOs like Golos of being fronts for foreign states seeking to destabilise Russia, our correspondent says.
Golos used to be partly funded by the United States Agency for International Development (USAID), but that body ended its work in Russia last year on an order from the Russian authorities.