"The prosecutor has decided not to prosecute my client," and he will be released shortly, lawyer Niels Anker Rasmussen told AFP.

Two more lawyers representing the other two suspects told Danish media the case against their clients had also been dropped, and they too would be released.

Prosecution could have caused a legal headache as the Scandinavian country has to date never transferred piracy suspects to its territory and has no extradition agreement with the countries along the Gulf of Guinea coast.

Rasmussen said the decision not to prosecute was also likely over fears that, after any prosecution, his client "could not be sent back home due to Denmark's obligations" under international conventions, and that "this might inspire others" to follow suit.

The three suspects were among four presumed pirates of unknown nationality arrested in the Gulf of Guinea in late November after an exchange of fire with a Danish navy ship, the Esbern Snare.

The three who will not be prosecuted have been held on that ship, while a fourth who was injured in the shootout is in hospital in Ghana.

It was not immediately clear whether charges would also be dropped against the fourth suspect.

The incident occurred on November 24 when the crew of the Esbern Snare, which was patrolling international waters in the area, attempted to board a pirate vessel.

Danish prosecutors accused the pirates of firing the first shot and sought to press charges over them attacking Danish soldiers, accusations they have denied.

Four more suspected pirates were killed in the firefight and a fifth fell overboard, the Danish authorities said.

The Gulf of Guinea, which stretches 5,700 kilometres (3,500 miles) from Senegal to Angola, is a troubled area for shipping companies, with 195 attacks on ships recorded in 2020 alone.

Of the 135 hostage-takings at sea that year, 130 occurred in the region, the International Maritime Office has said.