Chaos gripped Indian airports on Thursday after the country's biggest airline IndiGo cancelled over 1,200 flights, stranding thousands of passengers.

The company blamed the disruption on "unforeseen operational challenges," including technical glitches, bad weather and new rules for workers.

India's aviation watchdog ordered an investigation and demanded that IndiGo respond with plans to ease the interruptions, which have persisted since Monday.

Passengers vented their anger online, with one airport user on X describing "complete mayhem" with delays of up to eight hours and no staff on hand to help.

Some 1,232 IndiGo flights had been cancelled as of Wednesday, according to the company. The number of delays was not clear.

IndiGo said it was offering customers alternative travel arrangements and refunds while restoring its services.

The company acknowledged its "significantly disrupted" operations were partly due to new crew rostering rules having a "negative compounding impact."

The rules came into effect last month and aim to give pilots and crew more rest periods to enhance passenger safety.

In a meeting on Thursday with senior officials from the airline and from the Directorate General of Civil Aviation, IndiGo acknowledged that "more cancellations will continue for the next 2-3 days," according to a statement issued by the aviation watchdog.

Airline officials also said that "corrective actions are underway" with the aim of fully restoring operations by February 10, the statement added.

It said the aviation body demanded IndiGo submit "a detailed roadmap covering projected crew recruitment."

The disruption is another setback to the no-frills carrier, which has built its reputation on punctuality.

Last week, 200 of its planes were affected when Airbus issued an alert for an urgent upgrade for 6,000 aircraft worldwide.

India is one of the world's fastest growing aviation markets, hitting 500,000 daily flyers last month for the first time. (AFP)