Image copyright Reuters Image caption Mr Harper said Canada's participation was aimed at protecting Canadians

Canada plans to join the US-led campaign of air strikes against Islamic State (IS) militants in Iraq, its government has said.

A motion authorising the mission is expected to pass on Monday in the House of Commons.

The six-month mission will include CF-18 fighter jets and refuelling and surveillance aircraft, but not ground troops.

PM Stephen Harper said it was intended to "significantly degrade" IS.

Canada has more than two dozen military advisers already in Iraq.

The US has undertaken its own air strike campaign in Iraq for several weeks and in Syria for almost two weeks.

The plan put forward in parliament by Foreign Affairs Minister John Baird asks Canadian lawmakers to "recognise that the leadership of the terrorist group known as the Islamic State of Iraq and the Levant (ISIL) has called on its members to target Canada and Canadians at home and abroad".

Mr Harper said that if "left unchecked" IS could grow quickly.

"As a government, we know our ultimate responsibility is to protect Canadians, and to defend our citizens from those who would do harm to us and to our families," he said, according to broadcaster CBC.

Such an air strike mission must be debated and voted on in Canada's Parliament, but Mr Harper's Conservative MPs have a majority of seats, so it is expected to pass.

Canada's opposition parties have pressed Mr Harper to be more transparent about the plans.

Liberal Party leader Justin Trudeau said on Friday his party would not support the motion.

New Democratic Party leader Thomas Mulcair did not make a similar pronouncement but said he questioned the wisdom of getting involved in Iraq.

"The prime minister insists this mission in Iraq will not be allowed to become a quagmire," Mr Mulcair said, according to CBC.

"But isn't that precisely what our American allies have been facing in Iraq for the last 10 years?"

Canada did not join the US coalition that invaded in Iraq in 2003.

If the motion passes as expected, Canada will join a number of other countries that have joined the US in air strikes in either Syria or Iraq against IS, including Saudi Arabia, Jordan, the UK and France. Australia and Turkey have recent authorised military force for similar missions.​