An Arabic language TV channel says it has received new video from insurgents said to show four western aid workers kidnapped in Iraq. Al-Jazeera says the tape shows two Canadians, one Briton and an American seized in Baghdad last week. The station said the kidnappers have threatened to kill them unless prisoners in US and Iraqi detention centres are released by December 8.The hostages are members of the organisation Christian Peacemaker Teams – one of the few remaining aid groups operating in Iraq. Al-Jazeera earlier broadcast an appeal by the family of German hostage Susanna Osthoff who was also seized last week along with her driver. The German government says it wants to contact the gunmen who kidnapped the 43-year-old archaeologist. Her abductors have threatened to kill her unless Germany ends all support for the Iraqi government.