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.