Updated

A large bomb believed to be from World War II sighted in the River Mersey disrupted ship traffic Tuesday while demolitions experts worked to remove it.

A Royal Navy minesweeper spotted the 1,000-pound bomb near the entrance to Twelve Quays Dock in Birkenhead, across the Mersey from Liverpool, coastguard and navy officials said.

More than 250 passengers and crew on two ferries had to wait upstream as navy experts lifted the bomb and towed it toward a point 30 miles offshore, where it was to be detonated. A road tunnel and a rail tunnel under the Mersey also closed temporarily.

Liverpool and nearby cities were hit by more than 300 German air raids in 1940 and 1941, and hundreds of people were killed.

The navy regularly inspects British waterways to detect unexploded ordnance, which is still uncovered regularly across Europe.