Canada's new Liberal government will pull six fighter jets from air strikes against Islamic State (Isis) positions in Syria and Iraq within weeks fulfilling a campaign promise, a top official said. It is the most specific timetable for withdrawal yet provided by a government official.

The government of Prime Minister Justin Trudeau said it could contribute more effectively to the fight against IS by assigning more soldiers to train Kurdish militias battling the jihadist group.

"It's a matter of weeks, not months," Foreign Minister Stephane Dion told reporters, when asked when Canadian warplanes would cease operations against the group. "We're carrying out 2% of the air strikes. We're going to do something more efficient for the coalition."

In parliament the Conservative opposition, which committed Canadian planes to air strikes against IS while in government, asked why Trudeau was withdrawing from fighting just as other countries were stepping up their operations.

"The prime minister has ordered our CF-18s to stand down. Why is the prime minister stepping back from the fight when our allies are stepping up?" said Conservative interim leader Rosa Ambrose. Trudeau said that the Canadian military would remain involved, and that Canada would assist with humanitarian needs and refugees.