The White House has condemned the beheading of British hostage Alan Henning, following the release of a video appearing to show his killing by ISIS. 

"The United States strongly condemns the brutal murder of United Kingdom citizen Alan Henning by the terrorist group ISIL," said a White House statement.

The video, released on Friday, shows Henning kneeling in an orange jumpsuit. He says: "Because of our parliament's decision to attack the Islamic State, I, as a member of the British public, will now pay the price for that decision."

Henning, a taxi driver from Manchester, was in Syria as part of an aid convoy taking supplies to a hospital. He was abducted in December last year.

Another hostage is later identified as American Peter Edward Kassig.

Henning's beheading follows those of American journalists James Foley and Steven Sotloff, and British aid worker David Haines.

Shuja Shafi, secretary general of the Muslim Council of Britain, said it was "a despicable and offensive act."

"It is quite clear that the murderers of Alan Henning have no regard for Islam, or for the Muslims around the world who pleaded for his life," Shafi said.