Several other Russians are serving US prison sentences criticised by Moscow, including convicted arms dealer Viktor Bout, drug smuggler Konstantin Yaroshenko and hacker Roman Seleznev, the son of a parliamentarian.
A former US Marine who now works as head of security for a Michigan auto parts company, Mr Whelan holds US, British, Canadian and Irish passports as a result of his family’s emigration.
He travelled to Russia several times beginning in 2006 and was in Moscow for a wedding, his relatives said.
The well-connected news site Rosbalt claimed that he was arrested in the Metropole hotel near the Kremlin after receiving a USB stick with a list of employees of a state agency.
He is being held in Lefortovo pre-trial detention centre, a former KGB prison that is still known for its harsh conditions.
