Mauritania arrested Muammar Gaddafi's ex-spy chief, Abdullah al-Senussi, after he arrived on an overnight flight, officials said on Saturday, triggering a three-way tussle for his extradition.

Senussi, who for decades before the late dictator's fall inspired fear and hatred in ordinary Libyans, is sought by the Hague-based International Criminal Court on charges of crimes against humanity during last year's conflict.

But Libya's new rulers insisted he would have a fair trial there, while France - confirming it played a role in his arrest - stressed his alleged role in the 1989 bombing of an airliner over Niger in which 54 French nationals died.

"Today we confirm the news of the arrest of Abdullah al-Senussi," Libyan government spokesman Nasser Al-Manee told a news conference in Tripoli. 

"He was arrested this morning in Nouakchott airport and there was a young man with him. We think it is his son," he said, confirming a Mauritanian state news agency report that Senussi had been arrested with a false Malian passport arriving from Casablanca, Morocco.

France, which led Western backing for the popular uprising that toppled Gaddafi, said it had cooperated with Mauritanian authorities over the arrest and that it would be sending an arrest warrant to Mauritania.

A statement from President Nicolas Sarkozy's office noted Senussi had been sentenced in absentia for the 1989 bombing of a UTA airliner, in which 170 people were killed. Families of the victims immediately demanded he face justice in France.

An ICC spokesman said an ICC arrest warrant for Senussi also remained valid and requested that it be implemented, but Libya's National Transitional Council said Libya would insist Senussi face justice there.

"We insist that Senussi is extradited to Libya," NTC spokesman Mohammed al-Harizy said. "There are demands from the ICC and France to get Senussi, but the priority is to deliver Senussi to Libya."

While Mauritania is not a signatory to the Rome Statute governing the ICC, rights groups Human Rights Watch and Amnesty International both said Mauritania was bound by the UN Security Council to fully cooperate with the ICC. - Reuters