British Airways pilots are in the midst of a two-day strike that has disrupted an estimated 280,000 passengers and reportedly sent airfares rocketing.

The unprecedented 48-hour strike has grounded nearly 1700 British Airways flights, causing chaos for hundreds of thousands of passengers.

Fares to some international destinations have also soared by up to 2100 per cent.

CNN reports that a return easyJet flight from London to Nice, in the south of France, was costing up to £1272 ($2280) for less than two hours in the air. That was to depart Monday (British time) and return on Wednesday morning; returning on Tuesday was slightly cheaper, at £1055.

The fare – which did not include assigned seats, checked luggage or any food or drink – was sold out.

CNN said British Airways was charging £694 for the Nice-London flight on Wednesday night. By contrast, it has other September dates on the same route for sale for £58 – making this week’s flights nearly 22 times as expensive.

Flights on many routes popular with business travellers (such as London-Denver) are also sold out, while fares have been hiked on a host of others (such as London-Cairo).

The soaring fares come as the airline’s dispute with its pilots deepens. This week’s strike is the first of three days of planned action by the British Airline Pilots Association, the first strike by BA pilots.

Another day of industrial action is scheduled for September 27.

BA has called the strike action unjustifiable, saying its pay offer to pilots is fair. But BALPA wants British Airways to share more of its profits with its pilots.

“We hope we can find a way of resolving this dispute. We’ve been trying very hard to do so for the best part of nine months now but here we are now sadly having to take industrial action,” BALPA general secretary Brian Strutton told BBC radio.

He said pilots were willing to compromise but BA was not prepared to “budge”.

The airline dismissed a new offer by BALPA last week as an “11th-hour inflated proposal” not made in good faith. BALPA had said it would have called off this week’s strike if BA had engaged with the offer.

“We understand the frustration and disruption BALPA’s strike action has caused our customers. After many months of trying to resolve the pay dispute, we are extremely sorry that it has come to this,” BA said in a statement.

“Unfortunately, with no detail from BALPA on which pilots would strike, we had no way of predicting how many would come to work or which aircraft they are qualified to fly, so we had no option but to cancel nearly 100 per cent of our flights.”

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As a result, thousands of customers have had to seek alternative travel arrangements, and the airline has been criticised for its handling of communications with passengers before the strikes.

Britain’s Civil Aviation Authority is investigating the airline after it enraged some travellers by wrongly telling them their flights had been cancelled.

The regulator also reminded the airline to tell customers their rights. During the strikes, BA must offer passengers reimbursement for cancelled flights, alternate travel arrangements under comparable conditions or a new flight at a later date.

A spokeswoman for British Prime Minister Boris Johnson has urged both sides to end the dispute.

-with AAP