WASHINGTON - A Russian citizen pleaded guilty here Thursday to one conspiracy charge, admitting that she acted as an unregistered foreign agent to advance Moscow's interests.

In a court in Washington, Maria Butina, 30, reached a plea deal with federal prosecutors in which she admitted to trying to establish unofficial connections with US conservative groups, including the National Rifle Association. She also pledged cooperation with prosecutors in the subsequent legal process in exchange for a reduced prison time.

US media reported that Butina's prosecution is independent from the ongoing investigation led by Special Counsel Robert Mueller into alleged Russian interference in the 2016 US presidential election.

Butina admitted that at the behest of a "Russian official," she had worked with at least one US national, whom prosecutors believed to be Republican Party consultant and Butina's boyfriend Paul Erickson.

The Washington Post cited Department of Justice prosecutor Erik Kenerson as saying that the Russian official whom Butina referred to fitted the description of Alexander Torshin, the recently retired deputy governor of the Central Bank of Russia who is on the US Treasury Department's sanctions list.

Russian President Vladimir Putin said that Butina has no ties to Russian intelligence services, and that the whole case against her was thin, according to a Wednesday report by Russian media Russia Today.

Putin added that he asked all the heads of the Russian intelligence and security services and "no one knows anything about her at all."

Russian Foreign Ministry spokeswoman Maria Zakharova told CNN that Butina used the deal "to survive," describing the prosecution as politically motivated.

According to a statement by one of the prosecutors in the court, Butina drafted the "Diplomacy Project" in March 2015, suggesting that Russia forge "unofficial channels of communication" with US politicians to push for its interests.

Arrested without bail in July, Butina could face up to five years in jail, while her lawyer recommended zero to six months of imprisonment under federal guidelines, plus the possibility of further lowering of sentence. She will be deported to Russia after completing a jail term of whatever length.

Prosecutors have not agreed on any guidelines range so far but allowed leniency if Butina provides "substantial assistance." A hearing is scheduled for Feb 12.