LONDON, July 30 (Reuters) - A radar-related technical

issue in Britain's air traffic control system disrupted flights

for over four hours at major airports in London and elsewhere on

Wednesday, though the issue was later resolved and departures

were resuming.

"Our systems are fully operational and air traffic capacity

is returning to normal," NATS, the country's air traffic control

provider, said in a post on X.

"Departures at all airports have resumed and we are working

with affected airlines and airports to clear the backlog safely.

We apologise to everyone affected by this issue."

In a later update to Reuters, a NATS spokesperson said it

was a radar-related issue, "which was resolved by quickly

switching to the back up system during which time we reduced

traffic to ensure safety."

The outage, announced by NATS 20 minutes earlier, included

Heathrow Airport, Britain's largest and Europe's busiest.

"Flights at Heathrow have resumed following a technical

issue at the NATS Swanwick air traffic control centre. We are

advising passengers to check with their airline before

travelling," an airport spokesperson said.

Gatwick Airport and Edinburgh Airport also said operations

were resuming.

London City Airport had earlier also reported disruption. It

was not clear exactly how long the outage had lasted.

Ryanair said the disruption lasted for "over four hours" and

caused delays and several diversions, inconveniencing thousands

of passengers.

The Irish low-budget airline said the problem was "utterly

unacceptable" and called for Martin Rolfe, the chief executive

of the air traffic control provider, to resign.

"It is clear that no lessons have been learnt since the Aug

'23 NATS system outage and passengers continue to suffer as a

result of Martin Rolfe's incompetence," Ryanair chief operating

officer Neal McMahon said in a statement.

In August 2023, flights across Britain were disrupted after

the automatic processing of flight plans malfunctioned.

Last year, Britain's aviation regulator said NATS needed to

review its contingency plans for outages after the disruption,

which airline bosses said cost them over 100 million pounds

($133 million) in refunds and compensation.

($1 = 0.7534 pounds)