The armed group that took Western hostages in a deadly dawn attack in southern Algeria on Wednesday is demanding the release of 100 Islamists held in the country, a worker at the site told AFP.
"The kidnappers are demanding the release of 100 terrorists being held in Algeria, in exchange for their hostages," said the worker at the gas complex where 41 Westerners were seized, according to the militants, including seven Americans.
"(They) have demanded that these (detained) Islamists be taken to northern Mali," added the source, speaking by telephone.
Earlier, Algeria's Interior Minister Dahou Ould Kablia said that Algiers would not negotiate with the "terrorists," following the attack near the In Amenas gas field that also left two foreigners dead, including a Briton.
Meanwhile, a French catering company said that 150 of its Algerian employees were being held in the BP plant in Algeria where Al-Qaeda-linked militants claim to have taken 41 foreigners hostage.
It was not immediately clear if the catering staff were among Algerian workers who were, according to state news agency APS, released after the foreigners were seized.
Regis Arnoux, the executive chairman of CIS Catering, said the employees at the In Amenas gas field were being held against their will.
"They have not been allowed to leave the base," he said in an interview with the website of French newspaper the Journal du Dimanche.
"The information I have is that a group of around 60 terrorists from neighbouring countries attacked the base overnight. They took all the expatriates hostage, regardless of nationality, and tied them up.
"The Algerian staff are being held inside the site. The situation is very worrying.
"The Algerian army has surrounded the base, helicopters are flying over it. We fear the worst, there are many lives at stake."