WASHINGTON (REUTERS) - President Barack Obama on Saturday condemned the "barbaric murder" by Al-Qaeda of US hostage Luke Somers in Yemen during a rescue attempt by US forces.

"On behalf of the American people, I offer my deepest condolences to Luke's family and to his loved ones," he said in a statement.

"As this and previous hostage rescue operations demonstrate, the United States will spare no effort to use all of its military, intelligence and diplomatic capabilities to bring Americans home safely, wherever they are located.

"And terrorists who seek to harm our citizens will feel the long arm of American justice," he said.

Obama said he authorised the raid on Friday to rescue Somers and other hostages held in the same location. He said the United States had used every tool at its disposal to secure Somers' release since his capture 15 months ago.

He also thanked the Yemen government for its support.

"Luke was a photojournalist who sought through his images to convey the lives of Yemenis to the outside world," Obama said.

"The callous disregard for Luke's life is more proof of the depths of AQAP's depravity, and further reason why the world must never cease in seeking to defeat their evil ideology," he said.