WASHINGTON (AFP) - Fox News broadcast still images of Jordanian pilot Maaz al-Kassasbeh being burned alive by Islamic State in Iraq and Syria (ISIS) militants before posting full raw footage from the horrific execution video on its website.

Senior officials with the US network, the only major US media outlet to use video footage of Kassasbeh's death, said the decision was taken to highlight the "barbarity" of the ISIS group.

"After careful consideration, we decided that giving readers of FoxNews.com the option to see for themselves the barbarity of ISIS outweighed legitimate concerns about the graphic nature of the video," said John Moody, Fox News executive vice-president and executive editor.

"Online users can choose to view or not view this disturbing content."

In a television news bulletin on Tuesday, Fox used graphic images of Kassasbeh's death in its "Special Report" programme.

"We feel you need to see it," anchor Bret Baier warned viewers before the images were shown.

"The images are brutal. They are graphic. They are upsetting. You may want to turn away. You may want to have the children leave the room right now."

Baier said the images were shown to "bring you the reality of Islamic terrorism."

The slickly produced ISIS video, running some 22 minutes and 30 seconds, can be viewed in its entirety on the Fox News website, with a notice to viewers "Warning: Extremely Graphic Video: ISIS burns hostage alive."

Kassasbeh's gruesome murder triggered a global wave of revulsion and outrage, with Jordan responding swiftly with the execution of two militant Islamist prisoners.

Other US networks have opted against showing any of the pictures or footage from the IS video.

"CNN is not showing images of the killing, which triggered global condemnation and prompted immediate promises of retaliation and protests in Jordan, one of more than 60 nations involved in the US-led coalition against ISIS in Iraq and Syria," CNN said in a statement.