A group of 27 members of the U.S. House of Representatives wrote a letter to the Barack Obama administration with a demand to ensure that Viktor Bout be extradited to the United States from Thailand.
"The American lawmakers describe Viktor Bout as an international arms dealer and a party to a conspiracy to supply a terrorist organization with weaponry, although no verdict has been passed in the Bout case so far," the Russian ministry said in a statement.
"Moreover, Thailand has terminated a criminal case against Bout, while he has not been proven guilty on charges brought against him in the United States. In this context, the U.S. lawmakers' public appeal cannot be regarded only as an attempt to put pressure on the executive and judiciary authorities of Thailand," the statement said.
"These actions on the part of parliamentarians in a nation that purports to be an example of rule of law and observance of human rights looks embarrassing, to say the least," the document said.
Bout, 41, was arrested in Bangkok in March last year during a sting operation led by U.S. agents. The United States accuses Bout of conspiring with others to sell millions of dollars worth of weapons to the Revolutionary Armed Forces of Colombia (FARC).
The former officer in the Russian army faces a life sentence if tried in a U.S. court, while Thai authorities earlier announced that they would not press charges against Bout.
Western law enforcement agencies consider Bout to be "the most prominent foreign businessman" involved in trafficking arms to UN-embargoed destinations, including the Democratic Republic of Congo and Angola.
UN reports say Bout set up a network of more than 50 cargo aircraft around the world to facilitate his arms shipments, earning the nickname "merchant of death."
In an interview published in a Russian newspaper in October, Bout said Washington fabricated charges against him after he had refused to work as an informant.
