LONDON (AP) — The wife of a British aid worker held hostage in Syria by the Islamic State group made a televised plea Tuesday asking her husband's captors to free him.

Alan Henning, a 47-year-old former taxi driver, was kidnapped in December after crossing from Turkey into Syria in an aid convoy. His wife Barbara Henning asked the militants: "Please release him. We need him back home."

In recent weeks, the militants have released online videos showing the beheading of two American journalists and a British aid worker, and threatened to kill Henning next. Henning's captivity, and that of other Western hostages, was kept secret for months out of concerns publicity would endanger their security.

Barbara Henning has previously released messages through Britain's Foreign Office appealing for the militants to get in touch with her family. Earlier this month she said she had received an audio file of her husband pleading for his life. She said Tuesday the family has had no other communication from the militant group.

Dozens of Muslim leaders in Britain have urged the Islamic State group to release Alan Henning.

His wife said she had been given hope by "the outcry across the world" over Alan Henning's imprisonment.

"Surely those who wish to be seen as a state will act in a statesmanlike way by showing mercy and providing clemency," she said.