Darfur - The kidnappers of two aid workers in Darfur say they will kill them, unless six French aid employees convicted of abducting children in Chad are retried.

Chad's pardons two years ago for the French aid staff, three months after they were jailed, sparked public anger.

The Aide Medicale Internationale staff, a French and a Canadian woman, were seized in south Darfur a week ago.

The kidnappers have also threatened to target French interests if their demands are not met.

Armed men kidnapped the pair from their compound in South Darfur's capital, Nyala, about 100km (65 miles) from the border with Chad on 4 April.

The group, who denied the charges, were sentenced to eight years of hard labour by a Chadian court, but were pardoned in March 2008 by Chad's president.

The kidnappers allowed one of their captives to speak to media by satellite telephone on Sunday.

It was the second kidnapping of aid workers since the International Criminal Court issued an arrest warrant last month for Sudanese President Omar al-Bashir for alleged war crimes in Darfur.

Four workers with Medecins Sans Frontieres were kidnapped at gunpoint from their Darfur home on 11 March and later released.

Sudan expelled 13 aid agencies immediately after the indictment of Mr Bashir.