Canada has temporarily banned most carry-on bags for passengers flying to the U.S. in order to alleviate airport screening delays.

Passengers may carry small purses, cameras, coats, laptops and musical instruments. Also, there are exemptions for passengers needing to bring aboard medical devices and items for baby care.

Officials say the ban will be in effect for at least several days.

The ban was effective Monday, two days after additional security measures were implemented at Canadian airports following the failed attempt Dec. 25 to blow up a Northwest Airlines jet.

The added security caused delays and prompted Transport Canada to call for screening help from the Royal Canadian Mounted Police.

The ban mainly affected U.S. gateways at Toronto, Montreal, Calgary and Edmonton