The head of the world's oldest Islamic movement has called for the release of Briton Norman Kember, abducted in Iraq.
Mr Akef said the hostages should be welcomed, not harmed
Mohammed Mahdi Akef, president of Egypt's Muslim Brotherhood, said Mr Kember and three other hostages were being held against Islam's principles.
"In the name of the Muslim Brotherhood worldwide I call for the western peace activists in Iraq to be released immediately," he said on al-Jazeera TV.
The group's captors are demanding all prisoners in Iraq be freed.
"Islam rejects the kidnapping of innocent people regardless of their aim, beliefs and opinion, Mr Akef said.
"All laws locally and internationally consider kidnapping a crime, particularly when it targets innocent peace activists who are known for their activity and solidarity for the Iraqi cause."
Mr Akef said the hostages were from a group which worked with Palestinian people "against Israeli aggression" and should be welcomed.
"Kidnapping will only distort the image of Iraq," he said.
The Muslim Brotherhood, while officially banned, is very influential in Egypt, with a surge in support for independents standing on its behalf in last month's general election.
Mr Kember, American Tom Fox, 54, and Canadians James Loney, 41, and Harmeet Singh Sooden, 32, had travelled to Iraq as a "gesture of solidarity" with Canada-based international peace group Christian Peacemaker Teams (CPT).
They were seized in Baghdad on 26 November.
The kidnappers - claiming to belong to a group called the Swords of Truth - have accused the men of being spies, a charge their employers deny.
The Swords of Truth group had said it would kill the group if all prisoners in Iraq were not released by Thursday.
But a report on Arab TV network Al-Jazeera said that deadline had been extended to Saturday.
In the video, Mr Kember is shown telling the camera he is "a friend of Iraq".
"I have been opposed to this war, Mr Blair's war, since the very beginning but I ask him now, and the British government, to do all that they can to work for my release and the release of the Iraqi people from oppression."
Prayers were said on Friday at Finsbury Park mosque in north London for Mr Kember's safe return from Iraq, and for 295 Iraqi hostages held in the country.
Earlier, a former Guantanamo Bay prisoner, Briton Moazzam Begg, had called for the hostages' release.
Mr Begg said: "When we were first granted release by Allah's mercy we came home to find that there were people who opposed the government in their brutal war waged against Afghanistan and Iraq and stood on the side of justice, and they were not Muslims.
"It is our sincerest belief that Norman Kember, the 74-year-old Briton and those with him are amongst those people, the many people who opposed this war from the beginning and were only in Iraq to promote human rights for the oppressed."
Meanwhile, on the BBC's Today programme Terry Waite, who was taken hostage in Beirut 1987 and held for five years, made "a plea for the release of this man".
"I applaud his bravery, I applaud his desire for peace," he said.
But he criticised Mr Kember for going into a "highly polarised" situation in Iraq.