The captured wife of a senior Islamic State leader who was killed in a weekend raid will face questions over what she and her husband knew about the group's treatment of hostages, including Americans, U.S. officials said.

The U.S. government believes the leader, Abu Sayyaf, was involved in handling foreign hostages, including Kayla Mueller, an American aid worker who was killed in February, U.S. security and law enforcement officials said.

The White House said on Saturday that U.S. military personnel based in Iraq had carried out a raid in eastern Syria aimed at capturing Abu Sayyaf and his wife, known as Umm Sayyaf.

Umm Sayyaf was captured by U.S. forces, but Abu Sayyaf was killed after "he engaged U.S. forces," the White House said.

U.S. commandos freed a Yazidi woman who appeared to have been "held as a slave" by Abu Sayyaf and his wife.

U.S. law enforcement and security officials said that Umm Sayyaf would likely be questioned by members of the High-Value Detainee Interrogation Group (HIG), an interagency unit created after President Barack Obama closed down a CIA counterterrorism program widely criticized for its use of torture.

The U.S. officials said they believed Abu Sayyaf had some direct interaction with Mueller and other hostages although they said his wife's role would likely have been limited.

A representative for Mueller's family had no comment.

U.S. officials and a source close to hostage families said Islamic State militants were still believed to be holding other Westerners hostage, including British journalist John Cantlie, but not any Americans.