Paris, Sep 3 (IANS/EFE): Reporters Without Borders Wednesday said it was "appalled" by the beheading of American journalist Steven Sotloff, calling it a war crime.

"This is an outrageous, disgusting and demented war crime that should be tried before an international court," said Christophe Deloire, the group's secretary general.

"Not content with developing a hostage industry, the Islamic State is taking its horror even further by staging the beheading of journalists in series," he added.

A video released by the Islamic State showed the beheading of American journalist Steven Sotloff.

The group executed another American reporter, James Foley, two weeks ago.

The Paris-based organisation, which promotes freedom of the press, said Sotloff, 31, had been captured and held since the summer of 2013 in northern Syria.

He specialised in covering the Arab world and reported for many US publications such as Time, Christian Science Monitor, World Affairs and Foreign Policy.