The BBC has said it was assured by Palestinian President Mahmoud Abbas that its Gaza correspondent Alan Johnston, kidnapped a month ago, was safe and well.
BBC Director General Mark Thompson told a press conference in the West Bank city of Ramallah: 'I appeal to all those who may have influence with the kidnappers to use their best endeavours to secure Alan's release safely and speedily.
'I would appeal to the people holding Alan Johnston to release him immediately,' he added on what the BBC said was a 'day of action' being held to highlight its correspondent's plight.
There has been no word on the fate of Mr Johnston, 44, since he was forced from his car at gunpoint as he drove home from work in Gaza City exactly one month ago on 12 March, the longest a Westerner has been held in the volatile territory.
He said he had met the Palestinian president on Wednesday evening.
Mr Thompson said: 'Abbas told me that he had credible evidence that Alan was safe and well. He assured me that the Palestinian authorities are fully engaged with Alan's case and are working to resolve it as soon as possible.'
Palestinian journalists, who have held numerous protests in support of Mr Johnston over the past month, drove a convoy of 30 cars with his picture to government and security offices in Gaza City, shouting 'Free Alan Johnston'.
The BBC was also to hold a simultaneous broadcast with CNN, Sky, and Al Jazeera as part of its 'day of action' marking the one-month anniversary.
Meanwhile, at a news conference in London, Mr Johnston's father, Graham, made an emotional appeal to his son's abductors.
He said: 'You have families. Please think about what this is doing to my family, including in particular the distress and deep, deep concern Alan's mother and sister have had to endure for all these long weeks.
'As I have said before, please let my son go, now, today,' he said, flanked by his wife and BBC staff.
Mr Johnston, whose posting in Gaza was due to end in April and had previously reported for the BBC from Afghanistan and Uzbekistan, became the latest of around 20 foreigners to have been seized in Gaza over the past year.
