The former chief of the navy in Guinea-Bissau has been arrested and is being transferred to the US, local media have reported.
Rear Admiral Jose Americo Bubo Na Tchuto was picked up on a boat in international waters near Cape Verde, a local broadcaster said.
He is described by the US as a kingpin in Guinea-Bissau's huge drugs trade.
The small West African state is a staging post for gangs smuggling cocaine from Latin America to Europe.
According to a report by the broadcaster RTC in Cape Verde - the island state off the west coast of Africa - US officials supported by Cape Verde police arrested Adm Na Tchuto and he is expected to face prosecution in the US.
There has been no official comment from US officials.
Fernando Vaz, a spokesman for Guinea-Bissau's government, confirmed the arrests to the Reuters news agency, saying the rear admiral had been arrested off the coast of Cape Verde in a boat flying the Panama flag.
The Cape Verde islands lie about 1,000km (620 miles) west of Guinea-Bissau.
The former navy chief is among a number of military figures in Guinea-Bissau the US believes are heavily involved in the drugs trade.
"They have been widely corrupted by these violent and well-financed drug gangs and Guinea-Bissau is a very small country, its vulnerable, its institutions are weak," Bruce Bagley, an expert on drug-trafficking at the University of Miami, told the BBC's Newsday programme.
"It also has a coastline that's filled with inlets and mangroves and places to hide so it's geographically well positioned," he said.
US officials imposed a travel ban and asset-freeze on Adm Na Tchuto in 2010.
"He was an intermediary and he was paid for his services… he was obviously in a position to look the other way and even to provide protection for these shipments as they were offloaded," Mr Bagley said.
As navy chief he would have also been able to provide protection as the drugs were directed to "European markets through a variety of different routes including private aeroplanes up to and including camel trains across the Sahel and into areas where they could cross the Mediterranean", he added.
The rear admiral was arrested after a failed coup in December 2011, but released in June last year in the wake of a successful putsch.
Last year the UN Security Council warned that renewed political instability was allowing drug-trafficking to flourish in Guinea-Bissau.
The current transitional government, which took over after the military-backed coup in April 2012, does not have full international recognition.