TORONTO - New restrictions on U.S.-bound flights are causing "very significant" delays and headaches for travellers at Canada's busiest airport Sunday.

A spokeswoman says new regulations imposed after an apparent terror attack was thwarted on Christmas Day have led to "a tough day" at Pearson International Airport, west of Toronto.

Trish Krale, with the Greater Toronto Airports Authority, says "there have been very significant delays" mostly felt by people flying to the U.S.

A 23-year-old Nigerian man, who claimed ties to al-Qaida, was charged Saturday with trying to destroy a Detroit-bound airliner.

Most of the U.S.-bound flights that have already departed from Pearson are listed as having left at least one or two hours late, and other flights are listed as being delayed by four or more hours.

Among the stricter regulations are passengers are to have nothing on the lap and no moving around the flight cabin in the final hour before landing and only one carry-on is bag allowed.

"If possible if people can even reduce that to zero that would be a lot easier," Krale said.

"Most of the delays are occurring -- or some of the delays are occurring -- because passengers come to the airport and they don't know that so then they're having to shuffle their baggage around."

More than 60 flights were listed as cancelled as of mid-day Sunday, but that is less than six per cent of the total daily flights at Pearson.

"None have been cancelled so far because of the regulations," Krale said.

The airport authority is asking travellers to leave plenty of extra time, to check their flight status before leaving home and to be patient.

Umar Farouk Abdulmutallab allegedly tried to light an explosive on a Northwest Airlines flight as it was about to land in Detroit after a flight from Amsterdam, but other passengers overpowered him.

The federal government ordered Transport Canada and the Canadian Air Transport Security Authority to assume a heightened state of vigilance.

Public Safety Minister Peter Van Loan and Transport Minister John Baird announced the new steps in a joint statement this weekend. Van Loan said he had spoken with U.S. Homeland Security Deputy Secretary Jane Lute regarding the incident.