LONDON — British air traffic authorities say they're restricting the number of planes flying across or taking off from the south of England after one of their two national control centers was hit by glitches.

Air navigation service NATS says that unspecified "technical problems" at its Swanwick control center meant it had to impose restrictions on the number of planes flying across the southern half of the country.

The service said that the restrictions may cause disruptions and that the organization is working to restore the service. NATS added that British airspace remains open.

The restrictions are "not really an issue" at Heathrow Airport, head of news Richard Scott said Tuesday, adding that there were only minor delays at Europe's busiest air hub.