Footage aired on Aljazeera showed the six sitting on the floor holding up their passports.

The station identified the men as employees of a Jordan-based company called Abu Jaafar al-Mansour and said they were being held by a previously unknown group.

The claims could not immediately be verified and government officials in Jordan could not be reached for comment as news broke of the captives. 

Australian threatened

Meanwhile, another group has threatened to kill an Australian captive unless his country withdraws all its troops from Iraq within 72 hours, Aljazeera reported on Friday.

Douglas Wood has urged 
foreign forces to leave Iraq

The station broadcast new pictures of Douglas Wood in which his head is shaved and he appears to be pleading for his life.

The 63-year-old Australian engineer is a contractor who was captured over the weekend and first appeared in a videotape released on Sunday.

Thousands of Iraqis, and more than 200 foreigners, including at least 30 Jordanians, have been taken captive in Iraq since Saddam Hussein's rule collapsed in April 2003.

Some captors have sought ransom, while others pursued political motives such as the withdrawal of foreign companies and troops from Iraq. More than 30 captives have been killed.