Three Canadians who are said to have joined Jabhat al-Nursra were "directly involved in the holding and harsh interrogation" of Peter Theo Curtis and Matthew Schrier, according to a media report.

Vice-President Joe Biden says America will follow the terrorists who have killed two American journalists "to the gates of hell."

The Islamic State (IS) has reportedly beheaded U.S. journalist Steven Sotloff, the second execution of an American journalist in the past two weeks.