Dmitry Ustinov, 46, was detained over a month ago at the Vilnius airport after he arrived from the U.S. to allegedly negotiate a sales deal for night vision equipment used by the U.S. military, the Delfi news portal reported Thursday.
Alexander Mamayev, the head of the Russian Embassy's consulate department, said Moscow had been already informed about Ustinov's detention and the embassy was assisting him.
"Our representatives visited him in detention as requested and gave recommendations on defense attorneys," he said in an interview.
Ustinov, whose detention was based on an arrest warrant from the U.S. state of Delaware, introduced himself to embassy representatives as an owner of weapons store in Moscow, Mamayev added.
Delfi said U.S. special services established that in 2010 Ustinov wrote an e-mail to a co-conspirator asking to buy him night vision equipment.
Between July 2010 and October 2012, Ustinov acquired and later sold at least 13 items of military-oriented night vision equipment including PVS-14 sights after smuggling them out of the U.S., the news portal said.
Ustinov is currently being held at Lukiskes prison in downtown Vilnius. The country's Prosecutor General's Office is waiting for an extradition request from the U.S., which a court will consider later.
If convicted in the U.S., where he is accused of illegal arms sales and smuggling as well as money laundering, Ustinov faces at least 20 years in prison.