Passengers wait to check in for U.S.-bound flights at Trudeau airport in Montreal on Monday. Lineups continued at airports across Canada on Tuesday, although the congestion was easing somewhat. (Graham Hughes/Canadian Press)

Lineups persisted at Canadian airports Tuesday as travellers bound for the U.S. continued to face beefed-up security measures, including strict new restrictions on carry-on luggage.

The RCMP and local police officers have been dispatched to airports in Toronto, Calgary and Edmonton to help in the screening process and ease the congestion that developed after an in-flight bombing attempt on Christmas Day on a Northwest Airlines flight to Detroit.

Lineups for U.S. flights at Toronto's Pearson airport were moving Tuesday, but at times have stretched down long corridors as passengers struggle to repack their luggage at check-in counters to comply with new rules. In Vancouver and Montreal, delays were reported, but passengers were still making their flights.

Transport Canada warned that passengers should continue to expect delays and to arrive three hours in advance of their scheduled flights.

Transport Canada has said it authorized the Canadian Air Transport Security Authority to use RCMP and local police officers to assist with some procedures specific to the screening process "to alleviate the immediate pressures at the security checkpoint."

Transport Canada employees were also called in to deal with additional security needs.

Travellers face pat-down screenings at security checks that can take up to five minutes a person and passengers are now barred from bringing any carry-on luggage aboard U.S.-bound flights, with some exceptions.

The federal department said the new security measures are temporary but will last at least "several days."

In Calgary, Joanne Hedges showed up at the airport with two toddlers and was trying to figure out what she could take on board.

"It kind of sucks, but it's life," she said. "We've got to live with it. So we're trying to make the best of it and be prepared with lots of snacks."

Umar Farouk Abdulmutallab, 23, of Nigeria was charged Saturday with trying to blow up a Northwest Airlines flight as the plane approached Detroit on Dec. 25. He's accused of igniting an explosive substance hidden in his pants. An al-Qaeda group claimed responsibility for the attempt on Monday.

With files from The Canadian Press