Icy conditions at Montreal鈥檚 Pierre Elliot Trudeau Airport and a computer glitch at Toronto鈥檚 Pearson International Airport have caused major delays for thousands of travellers Saturday.

Flights resumed in Montreal Saturday morning after freezing rain forced the airport to suspend all flights for three hours. The suspension of operations caused a backlog of flights, and some planes may be delayed for several days.

A message posted to the airport website Saturday afternoon advised travellers to consult their airlines. 鈥淐onditions are gradually returning to normal and will continue to do so throughout the day. Thanks for your understanding.鈥

The icy conditions affected about 145 flights, many of which were cancelled, said CTV鈥檚 Genevieve Beauchemin.

鈥淲hen Montrealers woke up, there was that thick coating of ice on everything鈥 and that鈥檚 what was causing the problem at the airport as well,鈥 Beauchemin told 麻豆影视 Channel.

Environment Canada lifted freezing rain warnings for Montreal and Quebec鈥檚 western regions early afternoon Saturday, but warnings remain in effect for most of the southern parts of the province. A total of 2 to 10 millimetres of freezing rain was expected to fall in the region by the end of the day Saturday, with the highest amounts expected just north of the St. Lawrence River.

The weather agency also ended its freezing rain warning for Ottawa. Freezing rain gave way to rain as temperatures rose above the freezing mark Saturday afternoon.

Meanwhile, at Pearson International Airport in Toronto, as though a thick fog engulfing the city were not enough, the airport ran into computer glitches that made it impossible for travellers to be checked in to their flights by customer service agents. Staff were forced to check passengers in manually, though self-service kiosks remained unaffected.

The slowdown began at around 5 a.m. A few hours later, the airport posted a message on its website alerting passengers that all airline counter check-in systems were down, and advised travellers to check in online before arriving at the airport.

The airport issued a statement on its website, saying IBM technicians were working with the GTAA to 鈥渋dentify and implement solutions.鈥 By late Saturday evening, it seemed the issues had still not been resolved.

The airport tweeted Saturday night: "If you're flying tonight, confirm flight status with your airline and use web check-in or self serve kiosks to ease the check-in process."

It later offered its thanks to "all agents and staff working around the check-in issue."

The computer glitch camejust days after the airport partially shut down during an extreme cold snap on Tuesday, stranding thousands of travellers and creating a backlog of passengers who saw delayed or cancelled flights.