People flying out of Toronto Pearson International Airport are being warned about delays getting through security as travellers wait in massive lines to get onto their flights.

Airport spokesperson Tori Gass said in a statement Monday passengers need to "pack their patience" and arrive early as Toronto Pearson experiences "longer-than-expected" wait times at security checkpoints.

When asked about the cause for the delays, the Canadian Air Transport Security Authority (CATSA) told CTV News Toronto they were experiencing issues with staffing.

"CATSA's screening contractors are not immune to the recruitment and retention challenges experienced by the broader commercial aviation industry," the CATSA said in a statement. 

The agency said they are addressing the challenge by ramping up staffing and continued information sharing with airline partners.

"Prior to the pandemic, resources could be cross-utilized more efficiently between the transborder and domestic and international checkpoints due to staggered passenger peaks," the CATSA said.

"As air travel recovers we are observing simultaneous peaks, which can result in passengers flooding more than one security checkpoint at a time, making the redistribution of resources to address these passenger volumes more challenging."

The CATSA said passengers are also increasingly opting to travel with more carry-on bags, which means longer processing times for travellers at security check points.

NDP MP Matthew Green said he was travelling through Toronto Pearson on Monday morning on his way back to Ottawa, and what he experienced was "an absolute gong show."

"Line up into the gate is at least 500-plus deep," Green wrote on Twitter. "There is no way I’m making this 8:10 Air Canada flight."

Another traveller wrote on Twitter he has "never seen delays like this at Pearson."

"It's a chaotic situation. Police are helping to control the lines," Doug Asp wrote.

Gass said in the statement employees in the terminals are "doing their best" to process passengers through security.

"We kindly ask passengers to treat employees with respect," she said.

HOW EARLY BEFORE SHOULD I ARRIVE BEFORE MY FLIGHT?

According to Toronto Pearson's website, passengers flying domestically should arrive at the airport 90 minutes before their flight.

For those travelling internationally, it is recommended that passengers arrive at least three hours before their scheduled departure time.