Lagos, Nigeria (CNN) -- Rebels in Nigeria's delta region said Thursday they have located three abducted French nationals and one more hostage, and are working with kidnappers to ensure their release.
"The Movement for the Emancipation of the Niger Delta can confirm that it has located the three abducted French nationals and another individual abducted in a separate incident on the same night," the group said in a statement.
"We are in negotiations with the abductors towards effecting a transfer of the men to the custody of MEND."
The rebel group said it will release more information on their health once the kidnappers free them. The statement by the group's spokesman Jomo Gbono did not give details on who the kidnappers were.
The three French nationals were kidnapped overnight in an attack on their oil-services ship off the coast of Nigeria, the company they work for said Wednesday.
There has been no claim of responsibility for the attack on the Bourbon Alexandre by several speedboats, the oil services company said in a statement.
Sixteen crew members were onboard at the time. Thirteen remained on the ship and were unhurt, the company said.
The company provides ship and underwater services to oil and gas clients worldwide. It declined to release any more information.
It was unclear where the fourth hostage was abducted.
MEND, the key militant group in the oil-rich Niger Delta, is an umbrella organization of several rebel groups. It has been battling the government for years over fairer distribution of the country's oil wealth.