Traffic at the Paris Gare du Nord train station was halted on Friday after a World War II bomb was found on tracks leading to France's busiest terminal, officials said.

The unexploded bomb was found "in the middle of the tracks" overnight during maintenance work carried out in the area of Saint Denis suburb, the national SNCF rail company said. In a statement, SNCF said that traffic would be stopped at the Gare du Nord until mid-morning at the request of police.

"We invite travelers to postpone their trip," it said.

All traffic to the train station, which hosts Eurostar trains, trains to the airport, high-speed and local services, was closed as Paris police worked to disable the device.

The Gare du Nord train station lies in the north of Paris and is the country's busiest rail terminal, serving an estimated 700,000 people each day, according to the SNCF.