A memorial service was held Saturday for British aid volunteer Alan Henning, who was beheaded by Islamic State jihadists in Syria.

His widow Barbara told the private service at Eccles Parish Church in Manchester, northwest England, that the 47-year-old taxi driver was a "selfless and caring" man. They had a son and daughter.

The family were joined by the brother and daughter of David Haines, from Scotland, who was also murdered by IS extremists.

Henning had travelled to Syria to help his Muslim taxi driver colleagues deliver aid to their fellow believers in a convoy.

He was kidnapped shortly after crossing the border in December last year and his murder was claimed by the IS group in a graphic video released on October 3.

"We must never forget the reason why he went to Syria and the reason he was taken from us -- for being what we all should be: selfless and caring," Barbara Henning said.

Henning was the fourth Western hostage murdered by IS militants since August.

Beheaded,IS
A handout image received from Britain's Foreign and Commonwealth Office on September 15, 2014 shows British aid worker, Alan Henning holding a child in a refugee camp on the Turkish-Syrian border. - AFP Photo

His murder outraged the Muslim community in Britain, moderates and hardliners alike.

Hundreds attended a memorial service for Henning last month at the Muslim Heritage Centre in Manchester.

In a statement released before the memorial, Barbara Henning condemned her husband's killers.

"These people are hiding behind a peaceful religion to carry out their crimes against humanity," she said.

"We know this because we have seen the outcry from Muslims across the globe, condemning their behaviour.

"I only hope that we can bring these people to justice or that they receive the justice they deserve in the next life. No god would ever condone the killing of innocent people."