MONTREAL - Canada's two largest airlines have cancelled scores of flights, affecting thousands of passengers, due to the massive hurricane that has flooded parts of Texas.

Calgary-based WestJet (TSX:WJA) says 25 flights between Calgary and Houston have been cancelled since Friday, impacting travel plans for 1,400 passengers.

It says aircraft are positioned to resume service when the situation on the ground has improved.

Houston's George Bush Intercontinental Airport says on its website that it should reopen for commercial traffic on Thursday at noon local time.

WestJet says it is tentatively planning to operate one flight that day and one on Friday. Extra flight segments will be added over the weekend to help transport passengers.

Air Canada has cancelled several flights between Houston and airports in Montreal and Toronto. It wouldn't provide details about the number of passengers affected.