WASHINGTON (WASHINGTON POST) - Russian national and gun-rights advocate Maria Butina traded sex for a position in a special-interest organisation, according to US prosecutors who asked a judge to keep her in jail before trial because of her ties to Russian intelligence services.

Butina, 29, faces federal charges that she illegally conspired to establish a back channel between Russians and American politicians during the last election cycle and operated as an unregistered agent of the Russian Federation in the US.

She appeared in Washington federal court on Wednesday (July 18), where a judge ordered that she remain detained until her trial.

"Because Butina has been exposed as an illegal agent of Russia, there is the grave risk that she will appeal to those within that government with whom she conspired to aid her escape from the United States," prosecutors said in a court filing on Wednesday. "Butina presents an extreme flight risk."

The allegations seem as if they're ripped from popular culture, echoing facets of this year's thriller Red Sparrow with Jennifer Lawrence, as well as the popular FX series The Americans. The show was inspired by a 2010 case in New York, when 10 Russian sleeper agents were arrested in the US and expelled in a prisoner exchange after pleading guilty.

Butina used a US citizen, who is not named by prosecutors but matches the description of political operative Paul Erickson, to gain access to an extensive network of Americans in a position to influence political activities in the country, prosecutors said.

She lived with the 56-year-old man, but appeared to "treat it as simply a necessary aspect of her activities," the US said.

"On at least one occasion, Butina offered an individual other than US Person 1 sex in exchange for a position within a special-interest organisation," prosecutors said.

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 FBI agents in April and she testified before the Senate Intelligence Committee in a closed session, according to a transcript.

"She's not a flight risk," Robert Neil Driscoll said at the hearing. "She's certainly not a danger to the community."

Prior to her arrest, "we have been offering to cooperate with the government the entire time and have been met with silence," Driscoll said. There was "simply no indication of Butina seeking to influence or undermine any specific policy or law," he said.

It was apparent Butina was getting ready to leave Washington, the US said. She cancelled her lease, sent US$3,500 (S$4,700) to an account in Russia and inquired about renting a moving truck, prosecutors said.

The FBI uncovered evidence that Butina appeared to be "in contact with officials believed to be Russian intelligence operatives" during her time in the US, according to the US.

Butina is accused of attempting to influence American politics by infiltrating groups such as the National Rifle Association. She's the latest Russian to be charged in an expanding investigation that on Friday led to the indictment of 12 Russian military intelligence officers who allegedly stole and disseminated emails from Democratic groups.

Butina is also well-connected to wealthy businessmen in the Russian oligarchy, according to prosecutors who allege her Twitter messages, chat logs, and emails refer to a known Russian businessman with deep ties to Putin's administration and who was listed in Forbes as having a net worth of US$1.2 billion.

"This person often travels to the United States and has also been referred to as her "funder" throughout her correspondence," prosecutors said. These businessmen could be in a position to offer her safe harbour, they argued.

Butina was likely in contact with the Russian Federal Security Service, known as FSB, throughout her time in the US, prosecutors said. They said they found in her contact list an email account with an FSB-associated domain.

During the execution of a search warrant, investigators found a hand-written note, entitled "Maria's 'Russian Patriots In-Waiting' Organisation," and asking "How to respond to FSB offer of employment?"

Earlier this year, FBI surveillance observed Butina having dinner with a Russian diplomat. That official, who left the US in March, was suspected of being a Russian intelligence officer, according to prosecutors.

The charges against Butina were made public just hours after President Donald Trump appeared to accept assurances from Russian President Vladimir Putin that his country did not try to influence the 2016 election.

Trump later issued a public clarification of his remarks, saying he misspoke and accepted the US intelligence finding of Russian meddling in the election, although he immediately followed up by saying it could've been someone else too.

The investigation into Butina's activities began before Robert Mueller was brought on as special counsel in May 2017 and is being handled by the Justice Department's national security unit.