US hostage killed in air strike in Syria: IS

DAMUSCUS, Feb 7 (agencies):  Islamic State said on Friday that an American woman hostage it was holding in Syria was killed when Jordanian fighter jets bombed a building where she was being held, but Jordan expressed doubt about the Islamist militant group's account of her death.

In Washington, U.S. officials said they could not confirm that the woman, 26-year-old humanitarian worker Kayla Mueller of Prescott, Arizona, had been killed.

Her family said in a statement on Friday they are hopeful she is alive and asked Islamic State to contact them.

Mueller was the last-known American hostage held by Islamic State, which controls wide areas of Syria and Iraq.

The group has beheaded three other Americans, two Britons and two Japanese hostages - most of them aid workers or journalists - in recent months. Mueller was taken hostage while leaving a hospital in the northern Syrian city of Aleppo in August 2013.

The group's latest claim, detailed by the SITE monitoring group, came just days after it released a video on Tuesday showing a captured Jordanian pilot, Mouath al-Kasaesbeh, being burned alive in a cage.

Jordan's King Abdullah, who was in Washington discussing how to deal with Islamic State militants when the video was made public, vowed to avenge the pilot's death and ordered a stepped-up military role in the U.S.-led coalition against the group.

Jordan said it had carried out a second straight day of air strikes on Friday on Islamic State positions.

Meanwhile: The parents of a US hostage who Islamic State (IS) militants say was killed by a Jordanian air strike in Syria say they are "hopeful" she is still alive. The parents of captured aid worker Kayla Jean Mueller urged IS to make contact with them, and to treat Ms Mueller as a "guest".

White House officials say they have seen no proof she was killed. IS released images of a ruined building where it says she died, but no images of the aid worker herself.It said that Jordanian jets had bombed the building on the outskirts of their Syrian stronghold, Raqqa.