The United States and France appear on the verge of taking a more active role in liberating Iraq's second largest city from the Islamic State, and Canada will support the effort by deploying an army field hospital and medical staff, Defence Minister Harjit Sajjan said Wednesday.

A French government spokesman has said allied nations are preparing for a co-ordinated strike on Mosul, which extremists have turned into a stronghold in the nearly two years since they overran the region.

At an air force base near Washington, U.S. Defence Secretary Ash Carter is hosting a meeting of countries, including Canada, who are taking part in the war against the Islamic State. They are planning the next phase of the campaign in conjunction with the Iraqi government.

Sajjan says Canada will add an extra medical unit to its current special forces training and assistance mission.

"There were gaps that needed to be filled in the coalition and one of them was the medical facility," Sajjan told CBC News in an interview.

The Role 2 hospital has limited bed space, but will be able to provide emergency care and evacuation for casualties coming back from the fight for Mosul.

He said the decision involves up to 60 personnel, but it will not mean an increase to the overall size of the Canadian deployment in Iraq.

The hospital will be set up for at least a year near the front lines, at an undisclosed location, west of the Kurdish regional authority's capital in Irbil.

PM Justin Trudeau says Canada is stepping up its contribution to modern peacekeeping 1:45

Sajjan insisted that the new deployment falls within the Liberal government's intention of playing only a supporting, and not a direct combat role, in the war against the Islamic State.

"Our mission has not changed," he said. "The Iraqi security forces, as I've stated; it's their responsibility on the ground. We are in an advise and assist function, helping them prepare for the planning and training of that (Mosul) operation."

Canadian special forces troops have been helping plan "shaping operations" for the retaking of Mosul, Sajjan said.

"We will be part of the wider coalition operation, within the context of the mandate of our government."

Last winter, Prime Minister Justin Trudeau announced that Canada would end its CF-18 bombing campaign in Iraq and Syria, and would instead triple the number of special forces trainer whose primary mission is to instruct Kurdish fighters in the finer points of combat.

The decision effectively tripled the number of troops on the ground to over 200. Many of them are still taking up position behind the front lines.

The Liberals have since announced that Canadian bomb disposal experts will join a separate NATO-led training mission, being conducted in neighbouring Jordan and soon in Iraq itself. The government has provided no details on that endeavour.

Canada's role in ISIS fight

As part of the reboot of the mission in February, the government also beefed up its intelligence gathering capability, notably with greater involvement of the country's electronic eavesdropping service, the Communications Security Establishment.

It also reportedly deployed specialists from the military's 21st Electronic Warfare Regiment, which intercepts and decodes enemy transmissions.

Sajjan, who visited Iraq after the NATO summit in early July, said the capability is "paying off in a tremendous way."

Earlier this week, there were news agency reports in Iraq that powerful Shia Muslim cleric Moqtada al-Sadr has instructed his followers to begin targeting U.S. troops, who are deploying to help Iraqi forces retake Mosul.

Washington recently announced it would dispatch 560 additional troops.

Sadr, whose Mahdi Army fought a long-running campaign against the U.S. occupation troops after the 2003 invasion, issued the statement on his website, saying American soldiers "are a target for us," but offered no other details.

Shia militias have played a prominent role, alongside Iraqi forces, in liberating territory from the Islamic State.

Sajjan said the Canadian contingent is cognizant of the threat and he's comfortable that appropriate security measures are in place.

He went as far as to note that the more robust system the Liberals put in place is not only watching the Islamic State, but other possible threats.

"Some of the additional intelligence capability we have put in was particularly for force protection of our personnel," he said.

The Canadians have also deployed CH-146 Griffon helicopters to Iraq. And while the defence department refused earlier this year to disclose whether they had been outfitted with heavy weapons, Sajjan said Wednesday that those aircraft are helping with the defence of Canadian troops.