The number of pilots involved in a wildcat strike at India's national carrier Air India rose to 150 on Wednesday, as the walkout forced the cancellation of more international flights.
Some 100 pilots walked out on the first day of the strike at the debt-laden airline Tuesday and by day two the number had increased.
"About 150 pilots representing the Indian Pilots' Guild have reported sick," K. Swaminathan, a spokesman for Air India, told AFP.
Air India said that four international flights, including two to New York, were cancelled on Wednesday due to the industrial action, after several were axed the previous day.
The airline, which loses nearly $2 million a day, is facing mounting problems due to rising fuel prices, competition from low-cost rivals and a record of labour disputes.
Air India has sacked 20 of the striking pilots and Swaminathan said the airline fired them because "their actions were illegal." The airline has also stripped the pilots' union of recognition.
Civil Aviation Minister Ajit Singh also called the strike illegal and said the government was open to talks once staff returned to work.
"Discussion and disruption cannot take place at the same time. It is totally unjustified not showing up for work," Singh told an Indian TV news channel.
The pilots are protesting against former Indian Airlines pilots, who moved to Air India when the two firms merged in 2007, also being trained for new Boeing 787 Dreamliner airplanes, saying the plan would threaten their career prospects.
The pilots ruled out halting their protest even as the Delhi High Court ordered them to stop their "illegal strike," saying the industrial action could cause "irreparable loss to the company".
"We are willing to talk, but the (Air India) management and the ministry do not appear to be serious about the matter," pilots' union spokesman Captain Tauseef Mukadam told AFP, as he vowed the strike would go on.
The Indian government approved a restructuring plan last month to help turn around the fortunes of the beleaguered carrier, but warned that its performance would be strictly monitored.
The airline flies 400 flights daily, including 50 on international routes.
It has 1,500 pilots of whom 500 fly long-haul international routes.
Singh said the striking pilots were jeopardising the future of the nearly bankrupt airline, which has not made a profit in five years and depends on government funds to fly.
The Indian government pumped about 12 billion rupees ($230 million) into the airline in the financial year 2010-11. It has not paid salaries to its employees for the past four months, the Press Trust of India reported.