Suspected Russian arms dealer Viktor Bout is being treated well in a Thai prison and there are no plans yet to extradite him to the United States, Foreign Minister Noppadon Pattama said on Saturday.

"We have assured Russian authorities that we will treat Viktor Bout within the law," Noppadon told Reuters a day after Moscow summoned Thailand's ambassador to Russia to protest Bout's detention since his arrest in Bangkok last month.

Bout, dubbed the "Merchant of Death" by some media, was nabbed in a U.S.-led sting operation and charged with trying to buy weapons for Colombian rebels.

Bout, who denies the allegations, sent an open letter from his jail cell earlier this week, appealing to Moscow for help in securing his release.

He said the charges against him were fabricated by the United States government, which wants Bout's extradition.

Noppadon said Bout was still under investigation for violating Thai laws by allegedly seeking to buy arms in Thailand.

"We have no plan to deport him. The United States has asked us to deport him, but this case is under investigation. It depends on the court and the Thai government cannot intervene," he said.

Russia's Foreign Ministry said Bout's rights had been violated while under arrest in Thailand, but it did not give details.

"As was stated to (Thai Ambassador) S. Dhirakaosal, Russia's foreign ministry believes Thailand's law enforcement bodies will investigate this case objectively and impartially," the ministry statement said.

Noppadon said Bout was being treated well in jail and Russian diplomats had regular access to provide consular services.

According to the United Nations and the U.S. Treasury Department, Bout ran a network of air cargo companies and sold or brokered arms that have helped fuel wars in Afghanistan, Angola, Liberia, Rwanda, Sierra Leone and Sudan.

He is charged in New York with conspiring to sell weapons worth millions of dollars to Colombia's FARC guerrillas.

The United States has given billions of dollars in military aid to Colombia to fight Marxist rebels and drug cartels.