Russian diplomats were granted access to Butina on Thursday after she was denied bail by a federal judge in Washington, DC, for being a flight risk.
"Despite stress and psychological pressure she went through during her arrest, she feels fine and has no health complaints… Mariia is finding it hard to get used to prison. But she stays vigorous, maintains her innocence and will defend it in court," the mission said in a Facebook post.
The Russian Embassy has also asked the United States for a formal explanation in the case of Maria Butina.
"We have officially requested an explanation from US authorities concerning the arrest of our citizen," the Embassy said on Facebook.
The 29-year-old Maria Butina was arrested earlier this week by US authorities and charged with conspiracy to act as a foreign agent and impersonating an agent of a foreign government. She denied both charges in federal court in Washington on Wednesday but was remanded in custody without bail, as she is considered a flight risk.
Initially the hearing was scheduled for July 24 but on Thursday the date was reset to July 25, according to the schedule posted on the US District Court for the District of Columbia’s website. Butina will face Judge Tanya S. Chutkan at the hearing set to begin at 10:15 a.m. local time (14:15 GMT).
Butina's attorney Robert Driscoll said in a statement on Tuesday that she is not a foreign agent and that all the charges filed against her are exaggerated.
Russian Ambassador to the United States Anatoly Antonov said on Wednesday that the Russian Embassy in the United States was doing everything possible to arrange a meeting with Butina and solve her problem as quickly as possible.
On Thursday, the Russian Foreign Ministry in a post on its official Facebook page said because of the arrest in the United States of Russian citizen Maria Butina a flash mob has been launched to support her. #FreeMariaButina. The post asked supporters to change their Facebook avatar to a photo of Butina, as the Russian Foreign Ministry itself has done.
Butina faces up to 15 years in US jail for acting as an unregistered agent for a foreign government and conspiracy.