James Foley
James Foley may have volunteered to be executed in order to save his fellow American hostages held together.Reuters

American journalist who was beheaded in a gruesome video posted this week by militant group, Islamic State, may have volunteered to be executed in order to save his fellow American hostages held together, reports have surfaced.

The British daily Telegraph has quoted Foley's younger brother Michael as saying that there was "no doubt" that the American scribe would have sacrificed his life adding that he had always been generous and kind.

Michael, who is 38 told the paper: "He truly cares more about others than himself. I think he was probably the strongest and most prepared for it. God forbid there's others. But you can see just from the clips, from the video, he wasn't afraid."

The brother's statement comes after GlobalPost, the news organization where James worked, published the full text of a letter on Thursday,  that was sent by the jihadist group to the family members, in which the militants warn: "We will not stop until we quench our thirst for your blood".

According to experts who have analyzed the letter, the chilling warning could have been written by "John" who has been identified as the person who killed the American in the video.

The letter addressed as "a message to the American government and their sheep like citizens" argues that the Obama administration has now returned "to bomb the Muslims of Iraq once again, this time resorting to Arial attacks and 'proxy armies', all the while cowardly shying away from a face-to-face confrontation!"

Asserting that the United States did not spare their women, children or elderly, the jihadists vowed that they would do exactly the same.

Described as a well-educated, intelligent person but also one of the most fanatic members of the extremist terror group, John was reportedly based in the city of Raqqa in Syria, which is an IS stronghold.

The shocking and widely discussed footage has rattled the nerves of the US government and has triggered a collective sense of consternation among Americans. The event is likely to further intensify US aggression on the militants with the Obama administration hinting that Pentagon could go to the extent of launching air strikes in the IS bases in Syria – in an act that would indirectly assist the Assad government, which it says should step down.

A native of Rochester, Foley was kidnapped in northwest Syria on Thanksgiving 2012, while he was covering the Syrian crisis, and had been considered missing until the video went viral online.

Foley, who had worked for the Boston-based GlobalPost and other news organisations, had been kidnapped by a group of unidentified gunmen and made his disappearance public in January 2013 with the hope of appealing for his release.

The journalist's mother, Diane Foley, praised her son on Tuesday for giving his life "to expose the world to the suffering of the Syrian people."