'Jihadi John' probably killed in US strike in Syria

US forces have carried out an air strike targeting the Islamic State (IS) group militant "Jihadi John", with a "high degree of certainty" he was hit, the Pentagon said on Friday.

The Pentagon confirmed that US forces carried out an airstrike in Syria targeting Mohammed Emwazi. He came to be known as "Jihadi John" after appearing in several gruesome propaganda videos depicting the beheadings of eight hostages, the Guardian reported.

British Prime Minister David Cameron is expected to make a statement on details of the attack later on Friday following reports from the US that the American military was 99 percent certain that he was killed in a drone strike.

"Emwazi, a British citizen, participated in the videos showing the murders of US journalists Steven Sotloff and James Foley, American aid worker Abdul-Rahman [Peter] Kassig, British aid workers David Haines and Alan Henning, Japanese journalist Kenji Goto, and a number of other hostages," Pentagon press secretary Peter Cook said.

"We are assessing the results of tonight's operation and will provide additional information as and where appropriate."

Emwazi was born in Kuwait in 1988 and came to the UK in 1994 when he was six years old. His parents reported him missing in August 2013 and were reportedly told by police, four months later, that he was in Syria.

In August 2014, he made his first appearance - with his face covered - in the IS video showing the beheading of Foley.

His nickname "Jihadi John" was given to him by a group of hostages, who described him as part of an IS cell they named "The Beatles" because of their British accents. In February 2015, his identity was confirmed as Mohammed Emwazi.