LONDON, April 11 (Reuters) - British Broadcasting Corporation Director-General Mark Thompson is to travel to the Middle East to appeal for the release of a BBC journalist who was abducted in Gaza.

Alan Johnston, who will have been missing for a month on Thursday, was kidnapped from his car and has been held longer than any other foreign journalist in Gaza.

There has been no claim of responsibility for the kidnapping nor word on Johnston's fate despite pledges by the new Palestinian unity government to find him.

A BBC spokeswoman would not give any further details about Thompson's trip but said the corporation had also joined forces with Al Jazeera's English service, Sky News and CNN to broadcast a programme as part of a day of action to raise awareness.

The programme will be broadcast on BBC World, BBC News 24, Al Jazeera English and Sky News with packages and live reports from the different broadcasters, looking at day-to-day life in Gaza as well as the threats facing journalists around the world.

"We don't think this has ever happened before," Richard Porter, head of news at BBC World, said in a statement. "All the broadcasters involved share a common aim to highlight Alan's case and to remind viewers of the dangers faced by their news teams more frequently than ever."

Palestinian journalists have also held a three-day strike to press their government to do more to secure Johnston's release.

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