Six French aid workers imprisoned for abducting African children were released on Monday after they were pardoned by Chad's President Idriss Deby, justice officials said.

Dominique Aubry, one of the members of the Zoe's Ark charity sentenced to eight years' hard labour by a Chadian court late last year came out of the prison in northern France where he was serving his sentence, television pictures showed.

"I will try to be cleared one day," he told reporters outside the prison in Caen. "I don't know how. We'll see," he said, before criticising some of the media coverage of the case.

Four others, including the group's leader Eric Breteau were also released. A sixth member, Nadia Merimi is in a hospital near Paris but she is no longer in detention, a justice ministry spokesman said.

The six were convicted in Chad of trying to fly 103 African children to Europe without permission and the pardon does not mean that their criminal records are cleared.

The charity workers, who had denied the charges, were flown back to France in late December and were serving their prison sentences there under a cooperation agreement.

In their court testimony in Chad, the six had said they believed they were trying to rescue war orphans from the conflict-torn Darfur region of Chad's eastern neighbour Sudan.

But U.N. and Chadian officials said most of the children were not orphans and came from Chadian border villages, where their parents had been persuaded to give up their offspring in exchange for promises of education.

Breteau avoided waiting reporters when he left Fresnes prison south of Paris but Gilbert Collard, a lawyer representing him and fellow detainee Emilie Lelouch, said earlier his client would speak out about the affair.

"They will be able to defend themselves as they were not able to defend themselves up to now," he told Reuters. "Once they are freed, they will have the means to speak freely."

The release of the detainees just five months into their sentences draws a line under a stormy period between France and its former colony although four of the group still face investigation in France for possible breaches of French law.

The episode sparked angry protests in Chad and the group was condemned as misguided and foolish by the French government but many in France were also angered by the tone of much of the comment coming from Chad.

France's diplomatic and military support helped Deby weather a rebel assault on the capital N'Djamena in early February, and the Chadian leader made it clear he was ready to pardon the French aid workers.