BERLIN (AP) — An American bomb dropped during World War II has been defused at the airport in the northern German city of Hannover in an operation that forced dozens of flights to be diverted.

Local authorities decided last week to search for possible bombs on Sunday after experts carrying out soundings of the soil ahead of apron resurfacing work detected magnetic interference at two sites. A 1,000-meter (1,100-yard) radius was sealed off and 54 flights diverted to other airports.

The town council in Langenhagen, where the airport is located, said experts unearthed and defused a 250-kilogram (551-pound) U.S. bomb. A second suspect object turned out to be a metal pipe.

More than 70 years after the end of the war, unexploded bombs are still regularly discovered during construction work in German cities.