All residents were told to leave a “red zone” around Nizza Street in the city's historic district, while another 50,000 in an outer perimeter were advised to either go or remain in their homes from 7:00 am (0600 GMT) until 4:00 pm.

Experts were called in to defuse a 500-pound bomb that British forces had dropped on the city more than 70 years ago.

Turin Mayor Chiara Appendino was present at the site and planned to also visit those who had been evacuated to buildings at a fairground on the edge of the city.

Airspace above Turin was closed during the operation as was the Porta Nuova train station which is located along Nizza Street.

Italian Major Elvio Pascale, who directed the operations, said a detonator at the tail end of the bomb had to be deactivated and that the most delicate part of the process could take up to seven hours to complete.

The heart of the bomb contained 65 kilos (140 lbs) of dynamite, authorities said.