A four day protest by screening staff at Toronto's Pearson Airport in October meant 250,000 passengers boarded aircraft without being searched properly, CBC said on Thursday.

The Canadian Broadcasting Corporation quoted an internal transport ministry report as saying the lapse had "severely compromised the traveling public." It said the "security screening process was circumvented... in some cases it was abandoned altogether."

The problem arose after screeners working for a private security company began working to rule, hand-searching all carry-on bags and creating long lines.

The screeners told the transport ministry that managers cleared the lines by allowing about 250,000 passengers to pass through with minimal or no screening.

In a letter to the transport ministry, workers quoted their managers as asking "Why are you searching bags?" They said the managers "wanted us to rush through the screening procedures."

The internal report said the managers' action "constituted a gross violation of pertinent legislation," CBC reported.

The chief spokeswoman for Transport Minister Lawrence Cannon could not be contacted for comment.

Data from the Airports Council International group shows that in the first third of this year, Pearson was the 29th busiest airport in the world.