The mediator said he had met the kidnappers in northeastern Mali's Timetrine region, a hilly desert area where sources had earlier said the kidnappers had likely moved the hostages from Niger.

Aides to a Malian mediator said they have also been told that Francoise Larribe, 62, who was seized along with her engineer husband Daniel Larribe, is ill.

"The Frenchwoman is sick. We've been told she had been undergone treatment shortly before her kidnapping, but that she needs follow-up care," one of the mediator's aides said.

She underwent chemotherapy shortly before her kidnapping, the sources said.

"The kidnappers said the hostages are alive and well-treated," said the Nigerian mediator.

He added that the "kidnappers are open to any negotiations, and said they will soon make their demand known, but that the fate of the hostages is in the hands of 'all the factions' of AQIM."