By John Irish and Abdoulaye Massalaki
PARIS/NIAMEY (Reuters) - Serge Lazarevic, a Frenchman who was kidnapped in northern Mali and was France's last hostage abroad, has been freed after being held by al Qaeda's North African wing for nearly three years.
The freeing of France's last hostage is a boost for President Francois Hollande but questions linger over a reported prisoner exchange and a possible ransom payment that led to Lazarevic being freed by the Sahara-based group.
The 50-year-old spoke on Tuesday to reporters at the French embassy in Niamey. He was flanked by Mahamadou Issoufou, the president of Niger who has been credited with helping secure his release.
"I would like to thank the people of Niger who have collaborated with France to get me freed ... I have lost 20 kilograms but I am OK. I am well," he said, smiling.
Hollande will greet Lazarevic, described by authorities as an engineer, on Wednesday at 0630 GMT at Villacoublay airport near Paris, the president's office said.
It said Lazarevic was in "relatively good health despite the very trying conditions of his long captivity."
France dispatched thousands of troops to scatter al Qaeda-linked militants in Mali last year but it has had to rely mainly on a network of regional negotiators to secure the release of a number of hostages held in the Sahel-Sahara band.
A Malian newspaper and two sources, who requested anonymity, said several Islamist-linked militants held in Mali were freed in exchange for Lazarevic's freedom.
"There were in all five prisoners who were exchanged for the Frenchman," said one source in northern Mali.
The sources and L'Independent, the Malian newspaper, said two Malians who were the main suspects behind the 2011 kidnapping were among those released.
One of them escaped during a Bamako prison break that killed two people in June but was later recaptured.
"NO MORE HOSTAGES"
Authorities from Niger and Mali were involved in the release, Niger's presidency said, but none of the governments involved commented on the reported exchange.
"France has no more hostages in any part of the world," Hollande told reporters in Paris.
Alain Marsaud, a former anti-terrorism judge who is now a lawmaker representing French overseas, had no doubt France paid a ransom in some form. "We managed to get prisoners from Malian or Nigerien prisons released. You have to choose.
"Either you adopt ... (U.S. President Barack) Obama's policy in which you don't negotiate and then you see your hostages assassinated, or you negotiate without admitting it."
A U.S. and a South African citizen held by al Qaeda in Yemen were killed on Saturday in an attempted rescue by U.S. special forces.
Hollande said in September that Paris neither paid ransoms nor exchanged hostages for prisoners. "That does not mean other countries don't," he said. "Some countries have done it to help us. I admit it."
Last month, Lazarevic was seen in a video posted by AQIM imploring Hollande to do everything to free him.
Philippe Verdon, another Frenchman kidnapped alongside Lazarevic, was killed by his captors in northern Mali last year.
(Additional reporting by Tiemoko Diallo in Bamako, Souleymane Ag Anara in Kidal and Alexandria Sage and Natalie Huet in Paris; Writing by David Lewis and Bate Felix; Editing by Mark John, Ralph Boulton, Toni Reinhold)