Public television in the Cape Verde Islands says U.S. authorities operating at sea have arrested a former navy chief of the small West African nation of Guinea-Bissau who is suspected of being a kingpin in the international drug trade.

Radiotelevisao Caboverdiana reported late Thursday that Rear Adm. Jose Americo Bubo Na Tchuto and four other Guinea-Bissau nationals were apprehended aboard a yacht in international waters in the eastern Atlantic Ocean. It said they took the five into nearby Cape Verde, a former Portuguese colony, from where Na Tchuto was flown to the United States.

Telephone calls to the Cape Verdean government and police rang unanswered Friday. Kristine Marsh, a spokeswoman at the United States Embassy in Dakar, which oversees diplomatic relations with Guinea-Bissau, declined to comment, referring reporters to the U.S. Justice Department.

The U.S. Treasury Department designated Na Tchuto as a drug kingpin in 2010 for his alleged role in the cocaine trade in Guinea-Bissau, freezing any assets he might have had in the United States. For at least a decade, Guinea-Bissau has played a key role in the drug trade. The country's archipelago of virgin islands has been used by Latin American cartels as a stopover point for ferrying cocaine to Europe, where prices have skyrocketed at the same time that demand for cocaine leveled off in North America.

A former Navy Chief of Staff, Na Tchuto is believed to have played a role in the arrival of a plane carrying hundreds of kilograms (pounds) of cocaine from Venezuela to Guinea-Bissau in July 2008, according to a statement from the Treasury Department. He later fled to nearby Gambia in August 2008, returning to Guinea Bissau over a year later. He apparently feared for his life, and sought refuge inside the United Nations Peacebuilding Support Office in Bissau, the country's capital.

Guinea-Bissau has been plagued by coups. The last few, including one last year, are believed to have been fueled by an internal power struggle over which wing of the military would control the drug trade. The arrest of Na Tchuto comes against the backdrop of another rumor of a looming coup in the capital.

Antonio Indjai, chief of staff of the the country's armed forces, told reporters Thursday that reports that a coup was under way were false.

"They're only speculation by people of bad faith that serve to destabilize the country," Indjai said in the capital of Bissau, according to comments reported by the Agencia Noticiosa da Guine-Bissau news agency.