Moscow’s Foreign Minister Sergey Lavrov told his US counterpart at the weekend that the accusations against a Russian woman arrested in the United States for serving as an agent of Russia’s FSB intelligence were “fabricated” and that she should be released.

Lavrov made the comments regarding Maria Butina, the woman in question, during a phone call with US Secretary of State Mike Pompeo while the two were discussing improving bilateral relations, the Russian Foreign Ministry said in a statement in the wake of the recent summit in Helsinki.

Butina is currently being held in custody while she awaits trial. US prosecutors believe that her alleged ties to the FSB make her a major flight risk. She currently accused of working with a high-powered Russian official and two unidentified American citizens in trying to infiltrate the National Rifle Association, a right-wing, pro-gun organisation in the United States that wields signifcant influence over the US’ domestic and foreign policy.

Lavrov said the actions of the American authorities that were responsible for Butina’s arrest were unacceptable and he called for her release as soon as possible.

They also talked over possible joint efforts aimed at improving the humanitarian situation in Syria as well as the “challenges” of Korean peninsula de-nuclearization.

Butina travelled to the United States in April 2015 with Alexander Torshin, then the Russian Central Bank’s deputy governor, and took part in separate meetings with Stanley Fischer, the former vice-chairman of the Federal Reserve, and Nathan Sheets, then-Treasury Undersecretary for International Affairs.

The two meetings have revealed a wide circle of high-powered connections that Butina sought to cultivate with American political leaders and special interest groups.

The meetings with Fischer and Sheets were arranged by the Center for the National Interest, a Washington foreign policy think tank that advocates staunchly pro-Russian views that are closely aligned with the Kremlin.

The meetings were documented in a Center for the National Interest report seen by Reuters that outlined its Russia-related activities from 2013 to 2015. The report described the meetings as helping bring together “leading figures from the financial institutions of the United States and Russia.”

Butina worked for Torshin, who has close ties to Russian President Vladimir Putin and served as his interpreter at various Washington events.

The Treasury Department in April imposed sanctions on Torshin and a number of other Russian businessmen and government officials in Putin’s inner circle.