WASHINGTON (REUTERS) - At least one other American is being held hostage in the Middle East, White House spokesman Josh Earnest told reporters on Tuesday following confirmation of the death of US aid worker Kayla Mueller.

"We have avoided discussing the individual cases of Americans who have been held hostage, but we are aware of other American hostages being held in the region," Earnest said at a briefing, in response to a question about whether Islamic State in Iraq and Syria militants were holding any other Americans hostage.

Earnest declined further comment.

"I'm not going to get into the specific discussions of the cases of individuals who are being held hostage, principally because we don't believe that it's in their best interests for me to discuss them publicly," Earnest said.

"But there have been public reports of at least one other American hostage being held in Syria," he added.

The family of Austin Tice, a journalist who disappeared in Damascus in August 2012, held a news conference in Washington last week about his case.