TAXI driver Alan Henning gave up Christmas with his family in the UK last year to deliver medical aid to refugees 6,400km away in Syria.

Now facing execution as a hostage of brutal IS militants, the 47-year-old is at the centre of growing discord between the so-called Islamic State and other terror groups.

Even the masterminds behind the September 11 terrorist attacks on the United States, al-Qaeda, have appealed to IS to release Mr Henning.

The Independent reports that al-Qaeda believes Mr Henning is an innocent aid volunteer who was genuinely trying to help suffering Muslims, and kidnapping him was a step too far.

It is further evidence that IS’s depraved campaign through Iraq and Syria is now repelling Muslims of all views and backgrounds, even terror groups with similar ideals.

MORE: Islamic State video claims to show execution of British prisoner.

“Al-Qaeda has been critical of ISIS in recent months. It understands how its behaviour will be perceived by the Western public,” Professor Peter Neumann, the director of the International Centre for the Study of Radicalisation, based at King’s College London told the Independent.

“Although the two groups’ underlying ideology is still very similar, Al-Qaeda is much more strategic. For example, it is not opposed to beheadings but realises it makes no sense to carry them out in the way that ISIS does because this tactic will lose them a lot of friends.”

IS has beheaded three Western journalists and aid workers so far, and warned in a video posted online on Saturday night that Mr Henning would be next.

The British SAS has admitted it cannot rescue Mr Henning because they don’t know where he is. Foreign Secretary Philip Hammond said Britain would play a leading role in the coalition against IS, but its ability to find Mr Henning had “limitations”.

Mr Henning was abducted on Boxing Day last year when IS militants stormed the medical convoy he was on board.