In the 29-page filing, prosecutors said Ms Butina has ties to Russian oligarchs, including one with a net worth of $1.2bn, and that she was previously was in touch with oligarchs about funding her trip to the US. These businessmen could be in a position to offer her safe harbour, they argued.

The 29-year-old former American University graduate student was set to appear for a preliminary hearing in the US District Court for the District of Columbia this afternoon.

Butina was charged in the Washington federal court with acting illegally as an unregistered agent for the Russian government while she lived in Washington over the past three years with her boyfriend, a veteran Republican operative.

Butina's lawyer told a judge at a July 16 hearing that she didn't make a run for it even after her home was searched by Federal Bureau of Investigation agents in April and she testified before the Senate Intelligence Committee in a closed session, according to a transcript. "She not only has deep ties to her country (with which the United States has no extradition treaty) but actually works on behalf of the Russian government".

Prosecutors outlined in a court document seeking her continued detention how she had maintained a web of people to support her mission in the USA, and was in touch with employees of the Russian FSB, the spy agency that succeeded the KGB.

"This happened with the obvious task of minimising the positive effect" of this week's Helsinki summit between Russian President Vladimir Putin and USA leader Donald Trump, foreign ministry spokeswoman, Maria Zakharova, told reporters.

The organization is not identified in the court documents.

Moscow denies US allegations it interfered in the election and Trump denies any campaign collusion.

The FBI uncovered messages shared in March 2017 between Butina and the official, who is presumably Torshin, after media articles were published about her exploits as a gun rights activist.

Finland’s biggest newspaper trolls Trump and Putin
The long-awaited meeting between US President Donald Trump and his Russian counterpart Vladimir Putin took place in Helsinki . A probe over allegations of Russian meddling in the 2016 USA presidential election has clouded Trump's presidency.

Authorities say the relationship with the operative, identified as "US Person 1" in court papers, should not be seen as a "strong tie" to the US, noting she "offered an individual other than US Person 1 sex in exchange for a position within a special interest organisation".

"The filing of this latest complaint is just further evidence of how far-reaching and carefully planned Russia's assault on American democracy has been", said a former US official with knowledge of the Russian Federation investigation, who spoke on the condition of anonymity because of the ongoing probe.

Chapman belonged to the network of so-called illegal intelligence operatives rolled up by the Federal Bureau of Investigation in 2010 and went on to enjoy a high media profile for some time afterward.

Her lawyer, Robert Driscoll, called the allegations overblown and has denied that Butina is a Russian agent. She stuck out - not only because there is no substantive gun rights movement in Russian Federation - because of the deep connections she made in Washington.

The gun rights group was not named.

She also had broader outreach to Republicans.

Butina's Facebook page includes numerous pictures of her and Torshin, as well as photos of her attending other events where she met well-known American politicians, including Wisconsin Governor Scott Walker. Photos from the event show Butina and Torshin meeting with Walker.

"I know Putin and I'll tell you what", Trump told Butina, "we get along with Putin..." She stood up and asked Trump whether he would end the "damaging" USA government sanctions on Russian Federation. "I don't think you'd need the sanctions".