The US has urged Rwanda to guarantee the man portrayed as a hero in a Hollywood movie about the Rwandan genocide a fair trial as it is set to resume.
Paul Rusesabagina has been charged with terrorism, murder and other crimes. His lawyers have denied the charges against him.
The US state department said it had engaged with the government of Rwanda at the "highest levels" in "Washington as well as in Kigali".
"We believe that the legal process adjudicating his case should be fair and transparent, should respect the rule of law, and it must be consistent with Rwanda’s own commitments and human rights obligations internationally," US State Department spokesman Ned Price told journalists.
He had been asked whether a fair trial was possible and if President Joe Biden's administration was planning to join a bipartisan group of US senators calling for Mr Rusesabagina's release.
The 66-year-old became famous after Don Cheadle played him in the 2004 film Hotel Rwanda, which depicts his efforts to save hundreds of people from being murdered during the 1994 genocide.
He left Rwanda in 1996 and sought asylum in Belgium. He later obtained a green card for the US, becoming involved in opposition politics in exile.
A fierce critic of Rwanda's President Paul Kagame, he says he was illegally abducted in Dubai last year and flown to Rwanda. The authorities say he was arrested under an international warrant.