Militants holding an Australian engineer hostage have issued a 72-hour ultimatum for Australia to start pulling troops out of Iraq (search), Arab television station al-Jazeera (search) reported Friday.

The station did not specify what the militants were threatening to do if their deadline was not met, but a number of previous hostages have been killed.

Al-Jazeera aired new footage of Douglas Wood (search), 63, showing rifles pointed at his shaved head.

In a separate video released May 1, a group calling itself the Shura Council of the Mujahedeen of Iraq (search) claimed responsibility for seizing Wood, a California resident who is married to an American. Wood, who has a serious heart condition, was shown pleading for U.S.-led coalition forces to leave Iraq to save his life.

Al-Jazeera said Friday "the Shura Council of the Mujahedeen of Iraq has given Australia 72 hours to begin withdrawing its troops from Iraq."

Australia contributed 2,000 troops to the U.S.-led invasion of Iraq, and about 300 remain in Iraq.

Australian Prime Minister John Howard has ruled out paying any ransom or meeting demands to withdraw his country's troops from Iraq. But he has said his government would do all it could to secure Wood's release.

Earlier Friday, Howard and Foreign Minister Alexander Downer said a task force that went to Baghdad this week had established that Wood was alive.

Their comments came after an Australian newspaper reported that the task force had been in contact with an intermediary, Sheik Hassan Zadaan.

The Sydney Morning Herald said insurgents argued aggressively that Wood should be executed. But Zadaan said the insurgents accepted the argument that Wood was an Australian contractor who did not work for a U.S. corporation or belong to the military, the newspaper reported.

Downer, who is in New York, said he discussed the hostage crisis Friday with Vice President Dick Cheney (search) after previous meetings with Secretary of State Condoleezza Rice and U.S. National Security Adviser Stephen Hadley.

Al-Jazeera also reported Friday that militants released a separate video purporting to show six Jordanian hostages and warned Jordanian companies not to deal with the U.S. military. The station aired footage showing the six sitting on the floor and 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 called al-Baraa bin Malek.

Those claims could not be verified. Government officials in Jordan could not immediately be reached for comment.

More than 200 foreigners have been kidnapped in Iraq since Saddam Hussein's regime collapsed in April 2003. Some kidnappers have sought ransom, while others pursued political motives such as the withdrawal of foreign companies and troops from Iraq.

The kidnappers have killed more than 30 hostages.