José Américo Bubo Na Tchuto, former head of Guinea-Bissau's navy, was transferred to the United States after being snatched in international waters near Cape Verde in an operation by US and Cape Verd agents, state TV in the Atlantic island state reported.
Bubo Na Tchuto has since 2010 been on a list of suspected drug barons drawn up by the United States, which has also imposed a US travel ban and asset freeze on him.
He is one of several military figures in notoriously unstable Guinea-Bissau alleged to be involved in helping Latin American drug cartels smuggle cocaine into Europe via Africa.
There was no immediate official comment by US officials, but Radio France Internationale said a New York court would later Friday inform Bubo Na Tchuto and four others arrested with him of the charges against them.
The head of Guinea-Bissau national radio, Carlos Gomes Nhafe, a friend of Bubo Na Tchuto, told Agence France Presse (AFP) he had received a phone call from the former navy chief, who has been involved in several failed coups in the impoverished former Portuguese colony.
"He called me this [Thursday] morning from Sal, in Cape Verde, to tell me he had been arrested and that he is en route to the United States," he said.
No military official in Guinea-Bissau would comment. But an intelligence officer, speaking on condition of anonymity, said the ex-rear admiral was "captured by American agents".
He said US agents had been present in Guinea-Bissau for two weeks and that it was probably these agents who had been involved in the capture.
Bubo Na Tchuto's wife said she had not seen her husband since Wednesday and that her requests to military high command for information on his whereabouts had drawn a blank.
"He left the house [on Wednesday] as usual in his car to do some shopping in town and he hasn't been back since," Cadi Balde told AFP.
The Cape Verde islands lie about 1 000km west of Guinea-Bissau.
Bubo Na Tchuto was accused of being the leader of a coup attempt in December 2011. He was arrested and later released with 18 others in June last year on orders of the country's current army chief.
Guinea-Bissau, a country of just 1.5-million people, has suffered chronic instability since independence from Portugal in 1974 due to conflict between the army and state.
Political instability and mismanagement have undermined the economy, which is mostly based on primary crops and subsistence agriculture.
Drug traffickers have turned the state, which is sandwiched between Senegal and Guinea where the African continent extends the farthest west toward South America, into a transit point for the cocaine trade.
Guinea-Bissau suffered its latest military-backed coup a year ago, and the current transitional government does not have full international recognition.
The United Nations Security Council last year said that drug trafficking in the troubled state had grown since the junta seized control in April. – AFP