Air India Express has sacked at least 30 employees, mostly cabin crew, over mass sick leave amid flight cancellations, officials said Thursday.

The terminations came a day after nearly 300 employees of the private airline called in sick and switched off their phones, leading to large-scale flight disruptions.

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The termination letter issued to the employees says that the mass leave "clearly points to a pre-meditated and concerted abstention from work without any justifiable reason".

The airline management has also given an ultimatum to the employees to join work by Thursday evening or face action.

Since Tuesday night over 100 flights, both international and domestic, were cancelled by the airline. Reports said 74 flights were cancelled Thursday.

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The cancellations have snowballed into a crisis for the budget airline, which is a subsidiary of Air India, owned by the Tata group.

The employees have been protesting against the new employment terms and alleged lack of equality in the treatment of staff. The crisis has hit the airline at a time when it is in the middle of a merger with AIX Connect (formerly AirAsia India).

A statement issued by the airline said it was making "every possible effort to minimise the inconvenience caused to our guests by this unexpected situation."

Meanwhile, the federal civil aviation ministry has sought a report from Air India Express on the cancellations of flights and asked the airlines to ensure facilities for passengers as per the norms laid down by the Directorate General of Civil Aviation (DGCA).