US to bring to justice those responsible for aid worker's death: Obama

WASHINGTON: US President Barack Obama on Tuesday confirmed the death of Kayla Mueller, a US aid worker who had been held hostage by Islamic State militants, saying the United States would "find and bring to justice the terrorists who are responsible."

Mueller's family also said in a statement that they were "heartbroken" to learn of her death and released a copy of a letter she had written in 2014 while in captivity.

Earlier IS claimed on Friday that Mueller 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.

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.

Pentagon chief offers condolences after US hostage's death

US Defense Secretary Chuck Hagel on Tuesday expressed his condolences to the family of Mueller, a US aid worker who died while being held hostage by Islamic State militants.

"The world is united in condemning ISIL's continued murder and imprisonment of innocents," Hagel said, using an acronym for the group. "As we join Kayla's family and loved ones in their grief, we also celebrate her selfless dedication to helping others. Her compassionate spirit will never be forgotten."