A capture from a video released by the Islamic State group shows Alan Henning threatened by an unknown militant. Islamic State Group

The wife of Alan Henning, a British national captured by Islamic State militants in Syria last December, called for her husband’s release Saturday in a statement issued via Britain’s Foreign Office. “I cannot see how it could assist any state’s cause to allow the world to see a man like Alan dying,” she said.

Henning, 47, a taxi driver from Salford, a town near Manchester, was seized while taking part in an aid convoy near Syria’s border with Turkey. Islamic State militants threatened to kill Henning in a video that showed the killing of another Briton, aid worker David Haines.

The Islamic State, also known as ISIS, emerged from obscurity this year to capture vast swaths of territory in Syria and Iraq, countries plagued by instability and war. Espousing a severe interpretation of Sunni Islam, the extremists have beheaded two American journalists, James Foley and Steven Sotloff, in apparent retaliation for U.S.-led airstrikes in the region. Islamic State militants have also threatened to kill an Iraqi journalist who refused to cooperate with the organization.

Here is the full text of Barbara Henning's remarks:

"I am Barbara Henning, the wife of Alan Henning.

"Alan was taken prisoner last December and is being held by the Islamic State.

"Alan is a peaceful, selfless man who left his family and his job as a taxi driver in the U.K. to drive in a convoy all the way to Syria with his Muslim colleagues and friends to help those most in need.

"When he was taken he was driving an ambulance full of food and water to be handed out to anyone in need. His purpose for being there was no more and no less. This was an act of sheer compassion.

"I cannot see how it could assist any state's cause to allow the world to see a man like Alan dying.

"I have been trying to communicate with the Islamic State and the people holding Alan. I have sent some really important messages but they have not been responded to.

"I pray that the people holding Alan respond to my messages and contact me before it is too late.

"When they hear this message I implore the people of the Islamic State to see it in their hearts to release my husband Alan Henning."