Thousands of passengers have been hit by the first-ever strike by British Airways pilots which has led to at least 67 flights being cancelled between Scotland and London.

The biggest walkout in the airline's history is causing disruption to tens of thousands of travellers across the UK.

At Edinburgh Airport there were 28 flights that were cancelled to or from Heathrow and Gatwick.

Some 27 flights between London Heathrow and Gatwick and Glasgow were cancelled as of Monday morning.

At Aberdeen Airport there were at least 11 Heathrow flights cancelled.

BA passengers have been advised to avoid airports during the two-day action, which started at midnight.

READ MORE: British Airways error over flight cancellations

Members of the British Airline Pilots Association (Balpa) have a long-running dispute over pay, and "almost all" UK departures and international departures scheduled for Monday and Tuesday have been cancelled.

BA has apologised for any disruption to services.

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

"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 our flights.

"We remain ready and willing to return to talks with BALPA.

READ MORE: BA pilots set to strike in dispute over pay

Our customer teams – supported by additional colleagues - have been working tirelessly to help as many as possible and to provide options, including a full refund or re-booking to a different date of travel or alternative airline."

Flights on BA CityFlyer, SUN-AIR and Comair are not affected.

BA said if passengers' flights are cancelled they should not go to the airport. Rebooking or applications for a refund can be maked through their website.

BA chief executive Alex Cruz has said the action was an "own goal" and part of a "cynical" action by the union. He also demanded fresh talks with no pre-conditions.

He said: "We want to resolve this dispute as quickly as possible for our customers and, frankly, for everyone that works at British Airways."

BA has offered a pay rise of 11.5% over three years but Balpa says its members wanted a bigger share of the company’s profits.

The airline said its offer would take the pay of some captains to more than £200,000.

The airline operates up to 850 flights a day, with most expected to be cancelled, affecting up to 145,000 passengers.

The Association of British Travel Agents (ABTA) said that those whose flights have been cancelled are entitled to a replacement flight or a full refund.

It advised that if booked on a package holiday and are unable to travel,  travellers should talk to the tour operator who may be able to offer you alternative arrangements.

If no alternatives are available, travellers are entitled to a refund of the package price.

But it warned that if travellers have made their own arrangements and the flight is cancelled, they may well be liable for cancellation charges for unused services such as accommodation and car hire.

ABTA said this may be covered by travel insurance but this is not always the case.