Kidnappers holding two foreign aid workers in Sudan's Darfur region said yesterday they will kill them unless Paris retried members of a French group convicted but later pardoned over the abduction of children from Chad.

An unnamed member of a group holding the two female aid workers captive and calling itself the Freedom Eagles of Africa also threatened to target French interests in Sudan, Chad and the Central African Republic if their demands were unmet.

Stephanie Joidon, a Canadian, and Claire Dubois, a French national, working for Aid Medicale International (AMI) were seized at gunpoint from their compound in the south Darfur settlement of Ed el Fursan on April 4.

"We demand France open the case of the Zoe's Ark criminals and judge them through a fair court," one of the abductors said by telephone.

"If the French government is not serious in negotiations with us and does not respond to our request, we will kill the two aid workers," he said.

Six members of humanitarian group Zoe's Ark were jailed in 2007 for flying children, aged between one and 10, out of Chad to Europe. Chad said they had no authorisation to take the children out of the country.

The six, who denied the charges, were sentenced to eight years hard labour by a Chadian court, but were pardoned in March last year by Chadian President Idriss Deby.

Ms Joidon, who was allowed by the kidnappers to speak to Reuters, said she and Ms Dubois were being treated well.

"We are OK, we have food and water and they are correct with us, but we can't wait to go home," she said.

The French foreign ministry declined to comment on the case.

AMI said yesterday it was leading negotiations to free its staff but declined to give further details "given the delicate nature of the affair and out of respect for the families concerned".