Airline passengers are likely to face travel disruption over the next two days, as strikes are expected across European Air Traffic Control services.
The strikes, due to take place in Italy and Portugal, will affect British Airways and easyJet flights to, from and over these countries. BA have said they are planning on using larger planes to help customers affected by cancellations.
The industrial action is being staged by two organisations in protest against the European Commission's Single European Sky initiative, which aims to consolidate air traffic services across the continent, NATS said.
The Air Traffic Controllers European Unions Coordination (ATCEUC) - an umbrella group that represents 14,000 members across 28 countries - is calling the strike for tomorrow, before members of the European Transport Workers' Federation (ETF) then walk out on Thursday.
Air traffic controllers in the UK will be working as normal tomorrow and on Thursday, despite industrial action being planned across Europe
An Air Traffic control company said it would be "to everyone's benefit" if aviation regulators held an inquiry following Saturday's major disruption to flights.
Nats has already started its own inquiry into the events when an internal telephone system problem at the company's Hampshire headquarters led to flight delays and cancellations.
Saying he deeply regretted the disruption, Nats chief executive Richad Deakin said the best way forward was an investigation by the Civil Aviation Authority (CAA) into "the level of contingency and resilience in UK airspace".
Air traffic control company Nats has "identified and corrected" the technical problem which caused delays to thousands of flights in the south of England.
In a statement, the company said:
Operations are now returning to normal and we are working with the airports, airlines and (Europe-wide organisation) Eurocontrol to clear the backlog of flights to ensure disruption is kept to a minimum.
Outbound delays from the UK have generally been limited to 20 minutes. We regret any inconvenience this technical problem has caused. However, our first priority will always be the safety of the flying public.
Air traffic control company Nats has issued a full statement on "technical problems" at its Hampshire control centre, which has caused delays to thousands of flights.
We are experiencing technical problems at our Swanwick control centre and we are working to restore full operations.
This has not resulted in the closure of UK airspace or the suspension of all flights in or out the UK.
However, to maintain safety, we are restricting the number of aircraft flying across the south of England and those taking off from airports. We regret any inconvenience this may cause; however, our first priority will always be the safety of the flying public.
We are taking every step to restore services and have contingency plans.
Air traffic control company Nats said it is restricting the number of aircraft flying across the south of England and those taking off from airports due to technical problems at its Swanwick control centre in Hampshire.