Four Chinese sailors who were kidnapped last month in the port of Libreville, the capital of Gabon, have been released, the Chinese consulate in Lagos said.
Nigerian security sources separately confirmed on Tuesday that the four had been freed in a military operation.
"The consulate general in Lagos cooperated with the relevant embassies and local Chinese enterprises and overseas Chinese groups to carry out rescue efforts, and the hostages were released safely," according to a statement posted on the consulate's website.
Consul-general Chu Maoming visited the freed sailors before they went home, said the statement, dated Sunday.
The four had been seized by pirates in Libreville harbour on December 22 2019. A Gabonese captain was also killed in the attack.
The statement did not give details of their release, but a source in the Nigerian security services said Tuesday that they had been rescued by a "combined team of the Nigerian Joint Task Force".
The forces took part in a mission, codenamed Operation Delta Safe, it said.
The rescue unfolded in seas off the estuary of the Escravos River in Warri South West, in Niger Delta, the source said.