The group claimed it captured the two men in Iraq and asked the US-led forces in Iraq to release all Iraqi detainees within 24 hours or they would be killed.

The tape had come from Al-Tawhid wa Al-Jihad group, allegedly headed by Jordanian Abu Musab al-Zarqawi.

It showed the two men, who were identified as Bulgarians, sitting in front of their captors with their hands cuffed.

The two captors in the video were carrying rifles and a rocket-propelled grenade launcher. On the wall behind them was their black flag with a golden circle.

One of the men read a statement, though his voice could not be heard.

Previous claims

The US military has branded Zarqawi - who has claimed
responsibility for the beheadings of an American and a South
Korean - as its number one target in Iraq, blaming him for much of the anti-US actions in the country.

Dozens of foreigners have been seized since April by various groups to force the withdrawal of foreign troops from Iraq or to deter foreigners from working with US-led forces.

"The group said the Bulgarian government bore responsibility
over the safety of its citizens because it has sent troops to
Iraq," said Aljazeera.

No immediate comment was available from Bulgarian officials,
and it was not clear whether the captive Bulgarians were
military personnel or civilians.

Bulgaria has around 470 troops in Iraq. 

The latest kidnappings intensified pressure on Iyad Allawi's
interim government, coming only a day after another group threatened to kill a Filipino unless Manila withdrew its troops from Iraq.

The interim government is heavily dependent on the presence
of around 160,000 US-led foreign troops for security, while it builds up its fledgling forces.