Days after the beheading of American photojournalist James Foley, Sunni militant group Islamic State (IS) has posted a video showing the beheading of another kidnapped American journalist Steven Sotloff, CNN reported.

Titled “A second message to America”, the video also threatens the life of British captive David Haines.

Sotloff speaks to the camera before he is killed, saying he is “paying the price” for US intervention, the news channel reported.

The masked IS figure in the video speaks to US President Barack Obama, telling him, “Just as your missiles continue to strike our people, our knife will continue to strike the necks of your people.”

Last week, Sotloff’s mother Shirley Sotloff released a video pleading with IS leader Abu Bakr al-Baghdadi not to kill her son.

“Steven is a journalist who travelled to the Middle East to cover the suffering of Muslims at the hands of tyrants. Steven is a loyal and generous son, brother and grandson,” she said.

“He is an honourable man and has always tried to help the weak.”

Sotloff appeared last month in an IS video showing the decapitation of Foley. The militant in the video warned that Sotloff’s fate depended on what Obama did next in Iraq.

Sotloff disappeared while reporting from Syria in August 2013, but his family kept the news secret, fearing harm to him if they went public, CNN said.

Out of public view, the family and a number of government agencies have been trying to gain Sotloff’s release for the past year.