Guinea-Bissau’s President Umaro Sissoco Embalo has accused a former navy chief with links to the drug trade and two accomplices of being behind a failed coup earlier this month.

Heavily armed men attacked government buildings in the capital, Bissau, on February 1 while Embalo was chairing a cabinet meeting. The president later told reporters he had escaped a five-hour gun battle unharmed and that 11 people, mostly among the government’s security team, had been killed in the fighting.

Embalo, who launched an investigation into what he described as a well-funded and tightly planned assassination attempt, said on Thursday former navy chief Admiral Jose Americo Bubo Na Tchuto and his aides Tchamy Yala and Papis Djeme were behind the coup bid and were among those arrested.

The three men named by the president were arrested in April 2013 on board a boat off the coast of West Africa by undercover operatives from the United States Drug Enforcement Administration (DEA), for their involvement in a high-profile US drug sting and conspiring to ship cocaine into the US.

The president said he saw Yala and Djeme at the government palace during the coup attempt and that Na Tchuto was not present but was also behind the plot.

“During the coup, I see them. I see them with my eyes. They want to make a coup and kill me and the prime minister and all the government,” Embalo said.

“When the shots were being fired in the government palace, Bubo was at the Marine Corps headquarters … and I heard the assailants say we are going to call him to send us reinforcements.”

The president also said that among those involved were the same people who killed former President João Bernardo Vieira in 2009. Rebels from Senegal’s Casamance region were also involved, he added.

Guinea-Bissau, an impoverished coastal state of approximately two million people lying south of Senegal, has suffered four military coups since independence from Portugal in 1974, its most recent being in 2012.

In 2014, the country pledged to return to democracy, but it has enjoyed little stability since and the armed forces wield substantial clout.