But a terse Defense Ministry statement, issued a day after reports of the clash emerged from Mali, gave no word of the fate of Michel Germaneau, a retired engineer kidnapped on April 22 by Al-Qaeda in the Islamic Maghreb (AQIM).

"(We) confirm that the French Army gave technical and logistical support to a Mauritanian operation to prevent an attack by AQIM against Mauritania," the statement said.

Malian officials said Thursday the military swoop involving unidentified aircraft took place in northern Mali where the French national was believed to have been held.

"The terrorist group targeted by the Mauritanian Army is the one that executed a British hostage a year ago and has refused to give proof of life or engage in negotiations to release our compatriot Michel Germaneau," the French ministry said.

It did not say whether the hostage had been located or where the military operation took place. But it said Mauritania's action had "neutralized" the group.

Spain's El Pais daily quoted diplomatic sources on Thursday as saying French special forces had staged a dawn attack aimed at freeing Germaneau, killing six militants but finding no sign of the hostage or of the base where he was thought to be held. El Pais said French forces located the base with US help.

It said the Spanish government had been informed at the last minute but not consulted about the operation, and was upset because the raid could increase the risk to the lives of two Spanish hostages held for the last eight months by AQIM.

French daily Liberation's well-informed defense blog said French special operations commandos took part in the operation and had been on a mission in Mauritania for several months.

AQIM set a deadline next week to kill Germaneau, who was seized April 22 in northern Niger, unless its demands for a prisoner swap were met.

It gave France 15 days from July 12 to arrange an exchange and said French President Nicolas Sarkozy would be responsible for Germaneau's life.