Berlin's main international Tegel airport halted operations for an hour on Wednesday after a World War II bomb was discovered on a building site, officials said.

Police bomb disposal experts were called in to disarm the 250 kilogram (550 pound) aerial bomb that was discovered by labourers in a northern section of the airport, Berlin airports spokesman Ralf Kunkel told AFP.

Operations were suspended just before 6:00 pm (1400 GMT) "for safety reasons", Kunkel said, resulting in five cancellations and the diversion of about 20 incoming flights to Berlin's smaller Schoenefeld airport.