Hong Kong's consumer watchdog has expressed deep concern over Greater Bay Airlines' decision to cancel flights in the coming weeks, after receiving complaints regarding the low-cost carrier.

The airline previously announced the cancellation of 128 flights in February and March, affecting around 5,500 passengers to places like Japan, Thailand and South Korea.

The Consumer Council said it received two complaints regarding flight delays or changes involving HK$7,964 as of Wednesday noon, and has since contacted the budget carrier to follow up on the incident.

"The council calls on airlines to prepare for emergencies in peak seasons, fulfil their service commitments, so as not to hurt the reputation of the air carrier and Hong Kong as an international aviation hub," the watchdog said.

Haiyan Song, associate dean of the Polytechnic University's tourism management school, said passengers might think twice in future before booking with the budget carrier.

"It's understandable from the passengers' perspective. They would be unhappy with this cancellation, because this disrupted their travel plans. In the future, when the passengers travel to the same destinations, they would think twice whether they would book [with] Greater Bay Airlines," he told RTHK.

"But if, in the future, the [airline] recovers from this crisis and provides good services, customers will gradually build their confidence in the airline."