The Al-Jazeera television channel said the militant group, which had threatened to kill the captives today, had extended the deadline until 10 December.
Al-Jazeera broadcast unverified video images of two presumed hostages whose faces were not shown.
In a video provided to the Al-Jazeera and Al-Arabiyah news stations, a cleric detained in Great Britain has appealed to the Swords of Righteousness Brigades to release the four men -- two Canadians, a Briton, and an American -- who were abducted on 26 November in Baghdad.
Abu Qatada, considered by authorities to be a spiritual leader of Al-Qaeda in Europe, said the hostages should not be punished because of the policies of their governments. Abu Qatada is being held indefinitely in Britain over alleged links to terrorism.
(news agencies)