Piracy is common off Nigeria and often linked to militants
Nine crew members of a French ship taken hostage at the weekend off the coast of Nigeria have been freed.
The ship's owner - Bourbon - did not say how it had secured the release of the vessel.
The Bourbon Leda and its crew of five Nigerians, a Cameroonian, two Ghanaians and an Indonesian were hijacked by unknown gunmen in speedboats on Sunday.
Piracy off Nigeria is a common problem, often linked to militants targeting oil firms and taking hostages for ransom.
It is not known if Bourbon - which provides specialist boats for the oil and gas industry - paid a ransom.
The Bourbon boat had left Bonny Island in the Niger Delta and was off the coast of Akwa-Ibom State when it was attacked.
Militants are still holding two British hostages taken from another oil services vessel in September last year.
The Movement for the Emancipation of the Niger Delta (Mend) say they will only be released if one of their leaders, currently on trial, is freed.
Militants say they are fighting for a bigger share of the country's oil wealth, but many attacks are carried out by criminal gangs looking to extort money from oil companies, the government says.
Nigeria's oil production has been cut by around a fifth since 2006, partly as a result of the violence by criminal gangs and militants.
US oil company Chevron announced on Wednesday it had resumed production at its main Nigerian terminal which had been shut down for three months.
Saboteurs had blown up the main pipeline feeding the Escravos terminal in Delta State in November.