Mounties are now helping to ease commuter chaos at Canada's major airports, as airline officials enact tough new restrictions for flights headed to the U.S.

Transport Minister John Baird called the RCMP Sunday night, and asked that officers be stationed at Canada's largest airports to help speed up security checkpoints.

The new restrictions came after the attempted Christmas Day bombing of a U.S. airline.

U.S.-bound passengers are no longer able to bring carry-on bags into the cabin of the aircraft, according to Transport Canada. The only items passengers may carry are:

• medication or medical devices
• small purses
• cameras
• coats
• items for care of infants
• laptop computers
• crutches, canes, walkers
• containers carrying life-sustaining items
• a special-needs item
• musical instruments
• diplomatic or consular bags

"Additional searches of passengers and their exempted items will continue. Delays can be expected so passengers are advised to arrive at the airport three hours in advance of their scheduled flight," Transport Canada said in a statement.

"These measures are expected to be in place at least for several days."

Besides the usual pre-boarding security checks that have been in place since 2001-- such as restrictions on liquids and gels in carry-on bags -- the new checks include additional physical pat-downs of passengers.

The long line-ups that marked Sunday appear to be shorter at most flight centres in Canada, and most flights to the U.S. departed on time Monday.

That's in contrast to Sunday, when dozens of flights to the U.S. were cancelled or delayed. At Pearson International Airport alone -- Canada's busiest airport -- more than 160 flights were cancelled. Those that did go were typically delayed by one to five hours.

On Monday, Pearson officials said operations were running more smoothly, after Air Canada consolidated some flights and operated larger aircraft on certain routes.

Longer lines around the world

Airports across Europe also reported some delays to U.S.-bound flights Monday, because of the new security requirements.

At London's Heathrow Airport, Europe's busiest air hub, there were delays of about an hour, but both British Airways and Virgin Atlantic said delays had been minimal.

In France, the Paris airport authority said security backlogs on flights to the U.S. early Monday had delayed overall traffic an average of one hour, but by the evening, the backlogs had cleared.

While fewer flights are being delayed, the lineups at check-in counters at Canadian airports continue.

Airports are warning that all passengers flying to the United States should allow a few hours to check in. Domestic flights are not facing the same delays and security checks.

Reports from Pearson on Monday suggested that with the extra security searches, it was taking U.S.-bound passengers about three hours to get through security.

Officials with the U.S. Transport Security Administration said Sunday that passengers should not expect to see the same thing at every airport.

The TSA said heightened security procedures could include more gate screening, added presence of law enforcement officers -- some visible, some not -- and bomb-sniffing canine teams.

With reports from The Canadian Press