The Liberian-flagged Monjasa Reformer was found off the coast of Sao Tome and Principe in the Gulf of Guinea.

The Liberian-flagged Monjasa Reformer had 16 sailors on board when pirates attacked it on March 25. Despite being owned by a Danish company, none of the crew was Danish.

When the 135-metre-long tanker was found by the French navy the following week off the coast of Sao Tome and Principe in the Gulf of Guinea, the remaining crew said six of their colleagues had been kidnapped.

“All six crew members who were kidnapped from the oil tanker Monjasa Reformer are now safely recovered from an undisclosed location in Nigeria,” Monjasa said on Monday.

It did not specify if any ransom was paid.

Monjasa CEO Anders Ostergaard said they “are in a relatively good health condition, given the difficult circumstances they have been under in the last more than five weeks”.

“They have all been receiving medical checks and are now being repatriated to their home countries to reunite with their families,” Ostergaard said.

The shipping company had previously said it had lost contact with the crew after pirates boarded the ship.

Pirates have long been a risk in the Gulf of Guinea, a major shipping route stretching 5,700km (3,500 miles) from Senegal to Angola. But since 2021, shippers say pirates have been raiding farther out in international waters.

Their violence and sophisticated tactics prompted pleas from shippers for a more robust foreign naval presence like the mission to curb attacks from Somali pirates a decade ago.

In recent years, some gangs have captured larger fishing vessels that  they use as “motherships”, or bases, to raid farther out to sea.

But the region, which sees a lot of traffic from oil tankers, has also seen a lull in activity in the post-pandemic era.

According to a report by the Maritime Information Cooperation and Awareness Center, three ships were attacked in the area in 2022, compared with 26 in 2019.

Two other attacks have been recorded in the region in 2023 so far.