Passengers on a Scoot flight from Bangkok to Singapore waited for nearly a day after the flight was cancelled due to an issue with the aircraft's air-conditioning and pressurisation system.

Scoot flight TZ297 had been scheduled to depart Bangkok's Don Mueang International Airport at 10.55pm Bangkok time on Friday (June 30) for Singapore.

However, passengers never got to board the original plane and several of them complained about the lack of information on when the next flight would leave.

Mr Eric Lim, who was supposed to be on the flight with his wife, told The Straits Times on Saturday that while waiting to board the plane, the staff "kept delaying, saying they are doing some checks".

He said they were updated about the delays in half-hour intervals and claimed the airline did not announce the cancellation of the flight for several hours.

This dragged on until 4am before the passengers were "dispersed discreetly", said the 35-year-old who is self-employed. He estimated that there were about 50 Singaporeans on the flight, along with Thai nationals and people from other nationalities.

He said some foreigners who were in transit missed their connecting flights.

In the end, frustrated at the lack of information and wanting to go home, Mr Lim and his wife booked their own Singapore Airlines flights and cancelled their Scoot flight.

Their new flights cost more than $600 for two people, while their discounted Scoot flights had cost about $300 for both of them.

He said they had asked about refunds but were told "it might be in gift vouchers".

Mr Lim said it was the first time he experienced such a delay. He said he wanted certification to prove that the flight had been cancelled but was told by crew that they could not give them the certificates and directed them to call a customer service centre.

"There is no standard operating procedure when things happen, and even at midnight, they kept asking us to call the Scoot call centre," he said. "But most of us are overseas and our connections are down."

Mr Lim and his wife arrived in Singapore at 1pm on Saturday, about 11 hours later than their original arrival time.

However, the other passengers waited until 8pm on Saturday, 21 hours after their original departure time, before they could take a flight to Singapore.

Several other disgruntled passengers posted on Scoot's Facebook page expressing their unhappiness.

Ms Tan Gchin wrote: "Flight TZ297 from Don Mueang Bangkok to Singapore delay and delay again."

She wrote angrily in a post at 7.33pm on Saturday about how the problem could not be solved even after a whole day.

Another passenger, Aretha Francine, wrote that there was "still no news" in her 3.31am post and said she felt like she was being kept prisoner.

"Staff is completely incapable of giving a timeframe for take-off," she wrote.

A Scoot spokesman told ST that there was an issue with the aircraft's air-conditioning and pressurisation system.

"As a result, the aircraft was grounded in Bangkok for further troubleshooting," she said. "Troubleshooting of the defective system has been completed and the defect isolated. Accordingly, the flight was rescheduled to 8pm Bangkok time (9pm Singapore time) on July 1."

She said guests were provided food and water, as well as hotel accommodation, in the meantime.

"Safety is of utmost importance to Scoot and we will spare no effort to ensure the welfare of our guests," she said.