Thousands of passengers were affected on Tuesday when nearly 400 pilots working for Indian airline Jet Airways called in sick to protest the firing of two colleagues, the airline said.

Spokesman for the airline A K Sivanandan said that over 100 of Tuesday’s 346 international and domestic flights were cancelled, including flights to New York, London and Brussels.

A statement from the airline said that the pilots’ strike action is illegal and it was not clear at present how long the strike would last.

Sivanandan had said two senior pilots were sacked for working against the company’s interests but did not disclose the nature of the dismissal.

Almost 400 pilots are demanding that Jet Airways management immediately re-hire the fired pilots.

Jet Airways has offered a full refund to passengers whose flights were affected by the strike action.