Officials said several people were trapped under the rubble of houses and warehouses in the Emilia-Romagna region, where several building sites and workshops had reopened after the previous quake on May 20.

The earthquake had its epicentre not far from the city of Modena.

Italian television showed buildings shaking and collapsing, ambulances racing across towns and rescue workers battling to remove rubble.

Workshops and factories near Cavezzo, a village about 30km from Modena, suffered considerable damage.

Sports car-maker Ferrari and motorcycle firm Ducati closed their plants in the region for safety reasons.

"The situation is one of great fear and uncertainty," said Salvatore Iannizzotto, provincial head for the Modena police.

"The population was becoming more relaxed and slowly moving back into their homes. They have now left their homes again."