The British 5.4-tonne air-dropped bomb, called a Tallboy, was found at the bottom of the Piastowski Canal, near a ferry crossing, during work to deepen a waterway.
The operation to make the bomb safe is scheduled to last five days and has been described as the largest of its kind in Europe, state news agency PAP reported.
Over 750 inhabitants have to be evacuated from the zone where the bomb poses a direct threat, IAR added.
(pk)
Source: PAP/IAR