A New Delhi-bound Nepal Airlines Corporation (NAC) flight was not allowed to take-off from the Tribhuvan International Airport here by the country's aviation authority, leaving 254 passengers stranded, to put pressure on the national flag carrier to shift some of its international flights to the new Gautam Buddha International Airport to ease congestion, officials said on Tuesday.

The aircraft was not given clearance on Monday as its flight was not scheduled for the day, Tribhuvan International Airport (TIA) spokesperson Teknath Sitaula said.

The flight was cancelled after passengers were issued boarding passes, he said.

"The NAC had clearance to take off for New Delhi during the morning schedule but was not permitted to conduct the afternoon flight. Despite the fact that NAC officials knew there was no flight scheduled in the afternoon, they did not inform passengers, but rather distributed boarding passes to them," Sitaula told PTI.

According to an official of the Civil Aviation Authority of Nepal (CAAN), the regulatory body has reduced the number of NAC flights to New Delhi from TIA to 10 from 14 per week starting Monday.

The NAC was directed to conduct at least one flight to/from Gautam Buddha International Airport (GBIA) at Bhairahawa for three flights operating at TIA to manage the existing air traffic in TIA and for effective utilisation of the new airport, the official said.

According to the official, CAAN has sent multiple circulars to airline companies to conduct their flights from Bhairahawa, citing traffic congestion at TIA, however, the companies are not complying with the request.

"With the start of the winter schedule from October 30 till March 25 of 2023, CAAN has directed them to conduct one flight from GBIA per three flights from TIA," the official said.