WASHINGTON — A 29-year-old gun-rights activist suspected of being a covert Russian agent was likely in contact with Kremlin operatives while living in the United States, prosecutors said Wednesday in court papers that also accused her of using sex and deception to forge influential connections.

The woman, Maria Butina, was observed by the FBI dining privately with a Russian diplomat suspected of being an intelligence operative in the weeks before the envoy’s departure from the U.S. last March, prosecutors say. She also had contact information for people who investigators believe were employees of Russia’s Federal Security Services, or FSB, the successor intelligence agency to the KGB.

The allegations, made in court filings aimed at persuading a judge to keep Butina in custody, add to the portrait of a Russian woman who the Justice Department says worked covertly to establish back-channel lines of communication to the Kremlin and infiltrate U.S. political organizations, including the National Rifle Association, and gather intelligence for a senior Russian official.

Butina awaits trial on charges of conspiracy and acting as an unregistered foreign agent for Russia. A judge will hear arguments Wednesday on whether to keep Butina in jail as the court case moves forward.

Her lawyer has called the allegations overblown and has denied that Butina is a Russian agent.

Prosecutors also said Butina was regarded as a covert agent by a Russian official with whom she was in touch, with text messages discovered by the FBI showing how the official likened her to Anna Chapman, a Russian woman who was arrested in 2010 and then deported as part of a prisoner swap.

Authorities have not named the Russian official, but details in the court papers match the description of Alexander Torshin, a former legislator who is now a senior official in the Central Bank of the Russian Federation.

Torshin, who became an NRA life member in 2012, was among a group of Russian oligarchs and officials targeted in April by Treasury Department sanctions for their associations with Russian President Vladimir Putin and their roles in “advancing Russia’s malign activities.”

Prosecutors say the official directed Butina to use her contacts with the NRA and other conservative causes to gather intelligence on American officials and political organizations. She is also accused of trying to establish back-channel lines of communications for the Kremlin.