British Muslim leaders have made a plea for the safety of a British hostage threatened with beheading by Islamic State extremists in Syria.

The group said in a letter published on Thursday that hostage Alan Henning is a humanitarian aid worker who went to Syria to help victims of the civil war.

The religious leaders and community organizers ask the Islamic State group to "show him some mercy".

Henning's life was threatened in a video released on Saturday that showed him in the hands of the extremists who beheaded British captive David Haines and two US journalists.

The group said in the video that Henning would be next if Britain didn't end its support for US military strikes.

The 47-year-old Henning was taken captive in December.

The Associated Press