Kidnappers of four Western peace activists in Iraq have threatened to kill them unless all Iraqi prisoners are released from U.S. and Iraqi prisons.

The kidnappers issued the threat in a videotape broadcast Saturday by the Arab television station al-Jazeera. The videotape, dated January 21, apparently shows the two Canadians, one Briton and one American standing against a wall. The four disappeared on November 26.

Iraqi Insurgents Threaten to Kill Four Western Hostages

Al-Jazeera said the kidnappers issued a statement with the tape saying it was the "last chance" for U.S. and Iraqi authorities to save the hostages.

Iraqi Insurgents Threaten to Kill Four Western Hostages

The latest development comes a day after al-Jazeera broadcast a video of two Germans kidnapped last Tuesday.

Iraqi Insurgents Threaten to Kill Four Western Hostages

In Iraq Saturday, authorities say a policeman was killed and another wounded in a roadside bomb attack in the western city of Fallujah.