The ban by Capri mayor Paolo Falco forced several ferries on their way to the island from Naples and Sorrento in southern Italy to turn back.

The company charged with supplying the island with water said there had been a technical problem on the mainland on Thursday, and while that had since been fixed problems with the supply to Capri remained.

Falco warned of "a real emergency" and said that while there was still water on most of the island on Friday, local tanks were "running out".

"The emergency would be worsened by the arrival of the thousands of tourists which arrive on Capri daily", he said.

Locals could collect up to 25 litres of drinking water per household from a supply tanker, he said.

The ban, which does not apply to residents, will be in place until further notice.

Capri, in the Bay of Naples, is famed for its white villas, cove-studded coastline and upscale hotels. There are some 13,000 permanent residents but huge numbers of day-trippers in summer months.