LONDON — A technical issue briefly caused flight delays in Britain on Wednesday before engineers were able to restore the system, the air traffic control operator said.

The National Air Traffic Service, or NATS, said the glitch happened at its control center at Swanwick, near London. It required limiting the number of aircraft flying to ensure safety. Gatwick Airport said the issue affected outbound flights across the U.K.

About 30 minutes after issuing an initial alert, the agency said engineers had fixed the problem and that it was “in the process of restoring normal operations.”