Al Qaeda's North African wing threatened on Thursday to kill two Austrian hostages it had abducted in Tunisia if Vienna failed to secure the release of some of the group's members jailed in Tunisia and Algeria.

The three-day ultimatum starts at midnight on Thursday, al Qaeda in the Islamic Maghreb said in a statement posted on a web site.

Austrian Foreign Minister Ursula Plassnik said efforts were being made to secure the release of the hostages but noted that the demands were outside Vienna's jurisdiction.

"Austria would be responsible for the lives of the two hostages should the deadline come and our demands are not met," the militant group said.

"As you care for the safety of your citizens, we care to free our brothers who face the ugliest forms of torture at the prisons of Tunisia ... and Algeria," it said.

"We ask the families of the hostages and the Austrian public opinion to press their country's (government) to meet the demands of the mujahideen to preserve the lives of the two tourists," it added.

The demands and a list of the names of the group's prisoners were sent to Vienna through unidentified mediators, it said in the posting, which had pictures of the hostages identified in Austrian media as Andrea Kloiber, 43, and Wolfgang Ebner, 51.

The group, which has been waging a violent campaign against government forces and foreign interests in North Africa, said its members were jailed for confronting the new crusade against Islam.

Plassnik confirmed that Vienna had received the demands.

"They (kidnappers) have taken up contact with the Austrian side. Political demands have been made whose fulfillment do not fall within the responsibility of the Austrian side," she said in a statement.

"Appropriate efforts are being made to obtain the return of both hostages to Austria unharmed," Plassnik said.

PHOTO CAPTION

A undated file photo shows missing Austrian Wolfgang Ebner in Hallein.

Reuters