'British' Islamic State leader killed in U.S. air strikes

A leading British member of Islamic State and three other foreign militants have been killed in U.S.-led air strikes in northern Syrian town of Raqqa, monitoring group the Syrian Observatory for Human Rights said on Friday.

A U.S. official said earlier that a strike in the area probably killed the Briton known as "Jihadi John", who appeared in videos showing the killings of American and British hostages.

"A car carrying four foreign Islamic State leaders, including one British Jihadi was hit by U.S. air strikes right after the governorate building in Raqqa city," Rami Abdulrahman, Director of the UK-based Observatory told Reuters.

"All the sources there are saying that the body of an important British Jihadi is lying in the hospital of Raqqa. All the sources are saying it is of Jihadi John but I cannot confirm it personally."

US officials said the United States carried out an air strike in Syria on Thursday targeting the militant, who has been identified as Mohammed Emwazi, a British citizen.

The Pentagon said it was still assessing the effectiveness of the strike in the Syrian city of Raqqa, the de facto capital of Islamic State.

If his death is confirmed, it would be an important milestone in the U.S.-led campaign against the group and would come more than a year after U.S. President Barack Obama promised justice after the deaths of American hostages.

Dressed entirely in black, a balaclava covering all but his eyes and the bridge of his nose, Jihadi John became a menacing symbol of Islamic State brutality and one of the world's most wanted men.

The videos showed the killings of U.S. journalists James Foley and Steven Sotloff, U.S. aid worker Peter Kassig, British aid workers David Haines and Alan Henning, Japanese journalist Kenji Goto, and other hostages.

The strike came just as the United States seeks to increase pressure on Islamic State fighters, who have seized parts of Syria and Iraq, and who Obama has vowed to defeat.

The pressure includes U.S. plans to deploy dozens of special operations forces to Syria, deliver more weaponry to U.S.-backed Syrian fighters and to thicken U.S. air strikes against the militant group.