The Iraqi kidnappers of four missionary activists, including an Indian-Canadian, have threatened to kill the hostages if all prisoners in the US and Iraqi detention centres were not freed by Thursday.

Sources told UNI that the four hostages are believed to be in good health. But their whereabouts are not known.

A videotape aired by the Arabic TV Channel Al Jazeera showed the two Canadians eating while the British and American hostages were shown talking on camera but no sound was transmitted.

The two were calling on the US and British governments to withdraw from Iraq, Al Jazeera said.

The four missionaries, including an Indian-Canadian student, who had gone to Iraq on a peace mission, were kidnapped last Saturday.

The Indian-Canadian, Harmeet Singh Sooden, a 32-year old student of Auckland University in New Zealand [Images], and three other peace activists from the United Kingdom and the United States were on a peace mission in Iraq when they were taken hostage at gunpoint.

A previously unknown group calling itself the "Swords of Righteousness Brigade" claimed that two Canadians, including Sooden, a Briton and an American were ''...spies working for the occupying forces'' under the guise of being employees of a Christian group.

Sooden was working for the Christian Peacemaker Teams.

The US and Canada-based Christian Peacemaker Teams have blamed 'Illegal occupation' of Iraq by US and British troops for the kidnapping of the four workers.

The CPT has said in a statement, "The action of the US and UK governments" were responsible for the abduction of the four activists.

The organisation is an umbrella group for pacifist church activism. It issued a statement on Tuesday confirming that an armed group calling itself the "Swords of Righteousness Brigade" kidnapped the four men associated with their organisation in Iraq.

The CPT said it had a team in Iraq since October 2002, working with US and Iraqi detainees and training others in non-violent intervention and human rights documentation.

Many prominent religious and political leaders in Iraq and Palestine have appealed to the abductors to release the four abducted.