An unexploded WWII bomb discovered near tracks leading to France's busiest train station has severely disrupted rail service as police work to disable the device.

All domestic and international trains at Gare du Nord, Europe's busiest train station, came to a halt Friday after an unexploded World War II shell was discovered, officials said.

The police successfully defused the explosive device, which weighs more than 1,000 pounds and was found near tracks north of the French capital during landscaping work.