Canadian Prime Minister Paul Martin has condemned as "a callous act of terror" threats to kill four Western hostages in Iraq, two of them Canadians.
The hostages were innocent people who had no military links, Martin said.
"Let us remember these people are in the country on a humanitarian mission. They came to help the Iraqi people rebuild their society. They came to help build peace."
Iraqi kidnappers have threatened to kill Briton Norman Kember, American Tom Fox, 54, and Canadians James Loney, 41, and Harmeet Singh Sooden, 32.
The four - members of a Christian activist group - were seized in Baghdad last Saturday and were first shown in a video broadcast by Aljazeera on Tuesday.
The kidnappers want detainees in Iraqi and US-run prisons in the country set free by 8 December.
"I can reassure Canadians tonight that the full resources of the federal government are being made available. We will do all we can to get these men back home, home to their families," Martin said.
In Iraq, four more US soldiers, including a marine, have died in the troubled town of Ramadi.
During the latest operation against fighters in Ramadi, a soldier died of wounds sustained when a rocket struck his vehicle on Thursday.
Fighters on Thursday put on a show of strength in the city, 110km west of Baghdad, but the US command played down the appearance of armed men in broad daylight, saying it was a largely symbolic action for propaganda purposes.
Elsewhere on Friday, three soldiers died in a car accident in Balad, north of Baghdad, the Pentagon said.
This news follows the killing of 10 marines on Thursday during a night patrol near Falluja, 50km west of the capital, not far from Ramadi.
That incident marked the single largest military combat death since August.
A total 2125 US service personnel have died in Iraq since the March 2003 invasion, the Pentagon said.