More than 100 flights have been cancelled at Heathrow and a further 10 at Gatwick, while hundreds of others have been delayed.

BA confirmed in a statement issued shortly after 4pm the glitch had been resolved, but warned passengers to expect knock-on delays.

The issue has had a knock-on effect on flights throughout Europe, with BA flights delayed or cancelled at airports in Edinburgh, Glasgow and Belfast.

BA reported the outage early on Wednesday morning, which it said was affecting two separate systems – one relating to online check-in and the other to flight departures.

The airline said while the issues were affecting flights across its network, it has stressed the issue is not a global outage and only certain airports have been affected.

BA staff have reverted to checking passengers in manually, and passengers have been advised to get to their departure airport well ahead of schedule with lengthy queues reported at check-in desks.

Passengers booked on short-haul services departing Heathrow, Gatwick and London City airports have been offered a refund or the opportunity to travel another day (8-13 August).

In a statement, BA said: “We have resolved the temporary systems issue from this morning which affected a number of our flights today [Wednesday].

“We apologise to all our customers caught up in the disruption, and appreciate how frustrating their experience has been.

“Our teams have been working tirelessly to get the vast majority of customers on their way, with most of our flights departing.

Our flights are returning to normal, however there may be some knock-on operational disruption as a result of the issue earlier.

“We continue to advise customers to check ba.com for the latest flight information before coming to the airport.”