ISIS fighter in Raqqa, Syria
ISIS fighter in Raqqa, SyriaReuters

The family of British hostage Alan Henning on Tuesday said they have received an audio file of him pleading for his life, the BBC reported.

In a "further message for Islamic State (IS)", Henning's wife Barbara said IS "continue to ignore our pleas to open dialogue."

"I and people representing me continue to reach out to those holding Alan," she added.

Henning, a taxi driver from Eccles in Salford, was delivering aid when he was captured in Syria in December.

This is the second message from the Henning family, issued through the Foreign Office.

"I have seen Muslims across the globe question Islamic State over Alan's fate. The voices of the people have spoken out loud and clear,” said Barbara Henning.

"He was working with Muslims to help the most vulnerable within Syria. Nothing has changed. He went to Syria to help his Muslim friends deliver much needed aid,” she added.

The statement continued, "We are at a loss why those leading Islamic State cannot open their hearts and minds to the facts surrounding Alan's imprisonment and why they continue to threaten his life.”

"I have been told that he has been to a Sharia court and found innocent of being a spy and declared to be no threat. I implore Islamic State to abide by the decisions of their own justice system. Please release Alan."

Henning first spoke out over the weekend when she said there was no dialogue with her husband’s captors. She said she had sent messages to IS but had received no response.

Last week, British Muslim leaders called for Henning's immediate release in a letter in the Independent newspaper.

Henning’s whereabouts were only revealed last week when he was shown kneeling in the sand, wearing an orange jumpsuit, in a video produced by IS jihadists which also showed the murder of David Haines, another British aid worker.

Islamic State has released two previous videos showing the execution of the American journalists James Foley and Steven Sotloff. The group threatened to kill Haines at the end of the Sotloff video.