More than 1,500 flights have been cancelled as the company was accused of bullying its own staff by union bosses, who warned they could continue the action until the end of the year.

Some 280,000 people will be affected by the strike which is set to continue tomorrow, costing BA £80m in lost revenue.

BA and The British Airline Pilots’ Association (BALPA) are clashing after the union rejected a proposed 11.5 per cent pay rise for its pilots, taking their pay package to around £200,000 a year.

BALPA says that BA “has resorted to breaking agreements and threatening pilots who will strike, which is bound to make matters worse” after they emailed their 4,300 pilots on Friday warning that strike action would be a ‘serious breach’ of their contract.

The airline further threatened to withdraw a travel perk, where staff can book tickets for ten per cent of the full fare plus taxes, for three years if they chose to strike.

BALPA branded the airline’s behaviour “illogical and irresponsible” and “will further deepen the fall out with their pilots.”

Flights to New York, Delhi, Hong Kong and Johannesburg have all been affected, with the airline telling passengers: “If your flight is cancelled, please do not go to the airport.”

One passenger, Kenneth Farrington, told the BBC that he thought his holiday “was in ruins.”

Travellers have been offered full refunds, flights on different carriers, or the option to fly on a different date, but should not turn up at the airport without a confirmed flight.

Yesterday, 50 flights were cancelled over fears of a lack of space to park planes at Heathrow and Gatwick, and the knock on effect will last well into the week.

Long haul captains at the airline earn an average base salary of £167,000 a year, while co-pilots take home £70,000. British Airways say they made a “fair” offer of an 11.5 per cent pay rise over three years, plus a one per cent bonus.

The deal was already accepted by members of the Unite and GMB unions, which represent 90 per cent of British Airways’ staff.

BALPA says that now the company is in better financial health, its members should see a greater share of the profits and have a mandate for strike action until January, raising fears of Christmas travel chaos.

British Airways said yesterday: “We're extremely sorry for the problems caused by the strike action called by the pilots’ union, BALPA on 9, 10 and 27 September.

“We continue to be available for constructive talks with BALPA, on the basis that there are no pre-conditions to those talks.

“If you have a flight booked with us on those dates, it is likely that you will not be able to travel as planned due to BALPA’s strike action. We are offering all affected customers full refunds or the option to re-book to another date of travel or alternative airline.”

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Yesterday, BALPA General Secretary Brian Strutton said: “British Airways needs to wake up and realise its pilots are determined to be heard.

“They’ve previously taken big pay cuts to help the company through hard times. Now BA is making billions of pounds of profit, its pilots have made a fair, reasonable and affordable claim for pay and benefits.

“BALPA has consistently offered up chances for the company to negotiate a way forward. British Airways must now put the needs of its staff and passengers first and accept that its pilots will not be bullied or fobbed off.

“But the company’s leaders, who themselves are paid huge salaries and have generous benefits packages, won’t listen, are refusing to negotiate and are putting profits before the needs of passengers and staff.

“This strike will have cost the company considerably more than the investment needed to settle this dispute.

“It is time to get back to the negotiating table and put together a serious offer that will end this dispute.”

This is the second time in a month that BALPA have been involved in pay disputes with airlines, after Ryanair pilots were reportedly demanding pay rises of up to 121% according to the airline.

Ryanair accused BALPA of "excessive and unexplained demands for pay increases" and a secret memo seen by the Telegraph, which was drawn up by the airline, showed pay package demands of up to £350,000 a year.

Strike action has already taken place twice this summer, with more disruption planned for later this month.