Flights have resumed in Britain after a technical issue at air traffic control caused widespread disruption.

The National Air Traffic Service, or NATS, said the glitch happened at its control centre at Swanwick, Hampshire, at 4.05pm before restoring the system 20 minutes later.

NATS initially issued a statement saying it was "limiting the number of aircraft flying in the London control area in order to ensure safety."

Gatwick said "a technical issue impacting NATS is affecting all outbound flights across the UK" while Birmingham airport issued a similar statement "departing flights from many UK airports have been suspended."

NATS restricted flights across an area covering most of England and Wales, before confirming it had "restored the system."

"Departures at all airports have resumed and we are working with affected airlines and airports to clear the backlog safely," the body added.

The disruption comes at a busy time for holidaymakers and will ultimately delay some passengers. It has left many aircraft and flight crew out of position.

A Heathrow spokesperson said: "We are advising passengers to check with their airline before travelling. We apologise for any inconvenience caused."

The flight tracking website, flightradar24.com, reported an average delay of 48 minutes at Heathrow for departing aircraft at 5.30pm, an hour after NATS had restored its systems, and 89% of flights were suffering delays.

Paul Charles, a travel expert and chief executive of The PC Agency, a luxury travel group, told Sky News it was "a major outage".

He said it would take time to get operations back to normal, and long-haul flights will be prioritised.

"Long-haul traffic above short-haul traffic usually, because those long-haul aircraft are carrying more passengers," he said.

British Airways said the number of its inbound and outbound flights at Heathrow will remain restricted to 32 an hour.

BA added that the flow rate would return to the usual rate of 45 an hour from 7.15pm.

Ryanair called for NATS' chief executive, Martin Rolfe, to resign following the technical fault.

The airline claimed "no lessons have been learnt" since the August 2023 system outage affecting NATS' flight planning system, which grounded flights and disrupted trips for more than 700,000 passengers.

Ryanair's chief operating officer, Neal McMahon, described Wednesday's technical fault as "outrageous".

"Yet another ATC system failure has resulted in the closure of UK airspace, meaning thousands of passengers' travel plans have been disrupted," he added.

Liberal Democrat leader Sir Ed Davey called for an urgent investigation and also referred to the "utterly unacceptable" disruption two years earlier, when air traffic control was hit by a technical fault.

"With thousands of families preparing to go on a well-earned break, this just isn't good enough. The public deserve to have full confidence in such a vital piece of national infrastructure."

Transport Secretary Heidi Alexander said she was aware of the technical issue, but that "continued disruption is expected and passengers should check with individual airports for advice".

Flights departing or arriving at a UK airport, or aircraft operated by a UK airline arriving in the EU, are subject to rules concerning delays or cancellations.

Airlines may have to provide compensation, although there are exemptions for "extraordinary circumstances", according to the CAA (UK Civil Aviation Authority). (Sky News)