The father of missing BBC correspondent Alan Johnston has appealed for information, one week after his disappearance in the Gaza Strip.
Graham Johnston urged anyone holding his son to "just let him go", saying he was a friend to the Palestinian people.
Earlier, the BBC said it now seemed certain the reporter had been abducted.
The BBC's Middle East bureau chief Simon Wilson said he was disappointed there was no firm news, adding it was time to redouble efforts to find him.
On Saturday, Palestinian journalists demonstrated outside parliament in Gaza City in support of the correspondent.
Palestinian security officials say Mr Johnston was kidnapped from his car by masked gunmen on Monday.
There has been a series of abductions of Westerners in the Gaza Strip where law and order has deteriorated. All were eventually released unharmed.
In a televised appeal for information from the family home in Argyll, Graham Johnston said his son had made friends with many Palestinians while working in Gaza.
"This holding Alan is not doing the Palestinian people any favours, quite the opposite," he said.
"It is no way to treat a friend of the Palestinian people, and all I can say to the men who are holding Alan is: please let my son go, now, today."
The BBC says it has no official information about who may be holding Mr Johnston or where he is being kept.
Mr Wilson said: "Over the past week we have worked intensively with the authorities here in Gaza and elsewhere to try to locate Alan and we continue to receive assurances that everything possible is being done.
"However, it is disappointing that, after seven days, we still have no firm word either about his whereabouts or about his condition."
The BBC Deputy Director General, Mark Byford, has also commented on the disappearance of Mr Johnston.
"We just hope that everybody who has any influence in being able to secure Alan's release will act on it," he said on Monday.
"We ourselves will remain in touch with the people in the authorities who can help secure his release and we hope that it will be secured as fast as possible."
Palestinian President Mahmoud Abbas and Prime Minister Ismail Haniya are among those who have called for Mr Johnston's release.
He has been the BBC's correspondent in the Gaza Strip for the past three years - and the only foreign journalist from a major media organisation based in Gaza.
The BBC describes him as a highly experienced and respected reporter.
Mr Johnston, 44, was born in Tanzania and educated in Scotland. He joined the BBC World Service in 1991 and has spent eight of the last 16 years as a correspondent, including periods in Uzbekistan and Afghanistan.
His Gaza posting was due to come to an end at the end of next month.