A Russia court on Monday sentenced former US marine Paul Whelan to 16 years hard labour on spying charges in the country.
He was arrested in a hotel room in Moscow 18 months ago with a USB flash drive which security officers say contained state secrets, said a BBC report.
The Moscow City Court found him guilty of receiving classified information.
Whelan - who is also a citizen of the UK, Canada and Ireland - has previously denied the charge and said he thought the drive contained holiday photos.
He denounced the closed trial as a "sham" ahead of the verdict.
Whelan, who has visited Russia many times, had previously told the BBC that an old friend had turned up at his room uninvited and planted the drive.
"It's a case without any proof in over 16 months... That's intolerable," US Ambassador John Sullivan told the BBC in April.
He called Whelan's treatment, including the lack of proper medical care for a pre-existing health condition, "vile" and "inhumane".
( With inputs from IANS )