The Kremlin says that allegations against Maria Butina, a Russian woman accused of acting as an agent of Russia's government in the United States, are "groundless."
"We repeat, all allegations against her we consider to be absolutely groundless," Kremlin spokesman Dmitry Peskov told reporters on December 14.
For his part, Russian Foreign Minister Sergei Lavrov said he had "reasons to believe" the Russian had been kept in conditions designed to break her will and lead her to enter a false guilty plea.
"As far as I understand, this plea bargain -- the likes of which are common in the U.S. -- is part of a deal to get free and return home as soon as possible," Lavrov was quoted as saying by Russian news agencies.
Butina agreed to plead guilty in a U.S. court on December 13 to a conspiracy charge as part of a deal with federal prosecutors.
Prosecutors said Butina worked with a top Russian official to cultivate relationships with U.S. political organizations, including a powerful gun rights group and conservative activists as an agent for Moscow.
She is due to remain in U.S. custody until her sentencing, in February or later.
Since her arrest in July, Lavrov has repeatedly complained about her detention to Secretary of State Mike Pompeo, U.S. prosecutors have said.