Prosecutors said their allegation that Maria Butina offered sex in exchange for a position with a special interest organization was "mistaken," and based on a misinterpretation of text messages.

Russia's foreign minister told his U.S. counterpart on Saturday that a woman arrested in the United States on accusations she was a Russian agent had been detained on "fabricated charges" and should be released.

The Justice Department says Maria Butina worked covertly to establish back-channel lines of communication to the Kremlin and infiltrate U.S. political organizations, including the National Rifle Association.