Paris , France ( CNN ) -- Three French hostages kidnapped in Nigeria have been released , the French government said Wednesday . French Foreign Minister Bernard Kouchner announced their release `` with great joy and deep relief , '' saying the Nigerian authorities had told him the news . The three French nationals were taken hostage in Nigeria September 22 while on a boat belonging to the oil services company Bourbon . They all appear to be in good health `` despite difficult conditions while in captivity , '' Bourbon said Wednesday . They are undergoing medical and psychological tests under the company 's care in Nigeria before returning to France , the company said . Kouchner expressed his `` gratitude to the Nigerian authorities for the constant mobilization that led to the release of these three hostages . '' They were captured in an attack on their ship , the Bourbon Alexandre , Bourbon said at the time . It 's not clear who captured them , but rebels said the following day that they had located them . `` 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 September 23 . `` We are in negotiations with the abductors towards effecting a transfer of the men to the custody of MEND . '' The statement by the group 's spokesman Jomo Gbono did not give details on who the kidnappers were . MEND did not issue a statement Wednesday when the French nationals were released . It is not clear who the fourth hostage was . Sixteen crew members were on the Alexandre when it was attacked by speedboats , Bourbon said . Thirteen remained on the ship and were unhurt , the company said . The company provides ship and underwater services to oil and gas clients worldwide . 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 a more even distribution of the country 's oil wealth . CNN 's Christian Purefoy in Lagos , Nigeria , contributed to this report .
French Foreign Minister Bernard Kouchner greets the news with `` great joy '' in a statement released by his office. It is not clear who kidnapped them , but a rebel group said it found them .