The parents of BBC journalist Alan Johnston(photo), kidnapped in Gaza more than a month ago, appealed yesterday for news of his condition after an Islamist group said it had killed him.

Graham and Margaret Johnston, who live in Scotland, said in a statement this was a “desperately worrying time” for them.

“We make a heartfelt appeal to anyone who may have knowledge of Alan’s situation and wellbeing to contact the authorities in Gaza,” they said. “Our son has lived and worked amongst the people of Gaza for the last 3 years to bring their story to the outside world – and we ask every one of them to help end this ordeal.”

One of the few Western reporters based in the troubled territory, Johnston, a Briton, has not been heard from since his car was found abandoned on March 12.

An e-mail sent to media organisations, issued in the name of the Tawhid and Jihad Brigades, said the group had killed Johnston and would release a video of the killing later.