(Reuters) - The United States has refused a request from Russia that convicted arms dealer Viktor Bout be returned to his home country to spend the remainder of his 25-year prison term, a Russian Foreign Ministry official said on Saturday.

In this courtroom illustration Viktor Bout, a Russian arms dealer caught in an undercover sting operation by U.S. agents posing as Colombian guerrillas seeking weapons, sits during sentencing in New York April 5, 2012. REUTERS/Jan Rosenberg/Handout

Bout, 54, was sentenced in April after a Manhattan federal court trial jury convicted him on charges that he agreed to sell arms to people he thought were militants intent on attacking American soldiers in Colombia.

He was the subject of a book called “Merchant of Death” and inspiration for a film “Lord of War” starring Nicolas Cage.

Bout’s case has strained ties between Moscow and Washington - he said he was a legitimate businessman and the Russian Foreign Ministry argued he was convicted on unreliable evidence.

Konstantin Dolgov, Commissioner for Human Rights, Democracy and the Rule of Law at the Foreign Ministry told the Russian Interfax agency on Saturday that Russia’s bid to have Bout extradited had failed.

“We have received with concern the decision by the U.S. Department of Justice in relation to Viktor Bout,” Dolgov told Interfax. Dolgov said that Moscow “will continue to use all diplomatic and legal options to send Viktor Bout to Russia.”

In August, the Russian Justice Ministry said it had filed a formal request to the United States asking its counterpart to provide it with a copy of Bout’s verdict, which would allow it to start the transfer process if the American side agreed.

Albert Dayan, Bout’s New York lawyer, could not immediately be reached for comment. Representatives of the U.S. Department of Justice did not return requests for comment.

Bout, who Amnesty International says has been involved in embargo-busting arms deals to human rights abusers in Angola, Liberia, Sierra Leone and the Democratic Republic of Congo, was arrested in Bangkok in 2008 after a U.S. Drug Enforcement Administration (DEA) sting operation and later extradited to New York to face trial.

U.S. informants posed as arms buyers from the Revolutionary Armed Forces of Colombia, known as FARC, and met Bout in Thailand to buy an arsenal of military weaponry, which prosecutors said he agreed to provide.

Bout had lived untroubled in Russia, frustrating U.S. officials seeking his prosecution, until he was lured to Bangkok. Russia fought unsuccessfully for his repatriation from Thailand after his arrest.