Islamic State says female U.S. hostage killed in Syria

BEIRUT (Reuters) - The Islamic State militant group said on Friday that an American female hostage it was holding in Syria had been killed when Jordanian fighter jets hit a building where she was being held, the SITE monitoring group said.

In Washington, U.S. officials said they could not confirm that the woman, who has been identified as Kayla Mueller, had been killed. Reuters also could not immediately confirm the report.

Islamic State has executed five British and American aid workers and journalists in recent months.

A representative in the United States of Mueller?s family said the family had no information on Islamic State?s statement that she had been killed.

State Department spokeswoman Marie Harf told reporters during a briefing in Washington that "I cannot confirm those reports in any way."

"We have said that there are a number of Americans being held overseas, including still by the Islamic State. I'm not going to get into further details than that,? Harf added.

"We are obviously deeply concerned by these reports. We have not at this time seen any evidence that corroborates ISIL?s claim," Bernadette Meehan, spokeswoman for the White House National Security Council, said in a statement, using an acronym for the group.

Islamic State's claim comes just days after the group released a video on Tuesday appearing to show a captured Jordanian pilot, Mouath al-Kasaesbeh, being burned alive in a cage.

(Reporting by Mariam Karouny and Susan Heavey; Writing by Will Dunham; Editing by Kevin Liffey and Eric Beech)