The video purporting to show US journalist Steven Sotloff being executed is authentic, the White House says.

“The US Intelligence Community has analysed the recently released video showing US citizen Steven Sotloff and has reached the judgment that it is authentic,” said National Security Council spokesperson Caitlin Hayden on Wednesday.

• Obama calls for support in fight against jihadists

In the footage released by the Islamic State, Sotloff calmly addresses the camera to say he is a victim of President Barack Obama’s decision to press on with air strikes in Iraq against the jihadists. The video later shows a black-clad militant cutting his throat, before displaying his severed head.

Last month another American reporter, James Foley, was murdered in a similar fashion.