Berlin's Tegel airport has warned passengers to expect disruption on Friday morning when a World War Two bomb discovered near the capital's central train station is defused.

The 500-kilogramBritish bomb was found during construction work and all buildings within an 800-metre radius will be evacuated from 9am local time.

Planes coming in to land at Tegel, which is about seven kilometres away from the central station, may therefore need to be re-routed to avoid flying above the defusing site.

"Air traffic will be significantly limited tomorrow morning before and during the defusal," the airport operator told passengers via Twitter. Bus travel to and from the airport is also set to be disrupted.

A spokeswoman for Berlin Airports said more details would be made available during the day. Berlin police said a decision on whether to close the air space will be done by the bomb deactivation team.

More than seven decades after the end of World War Two, Germany still discovers more than 2,000 tonnes of live bombs and munitions every year.

Tegel airport was also briefly closed last August after a Russian-made bomb was discovered, forcing flights that evening to divert to the city's other airport, Schoenefeld.

Tegel is Berlin's busiest airport, serving over 21 million passengers a year. Major airlines flying to the airport include easyJet, Lufthansa, Eurowings, British Airways and Air France-KLM.