Venice flooded by unusually high spring tide

A quarter of Venice has been submerged by a near-record high tide for June, a time of year when such flooding is rare.

The water level in Italy's lagoon city reached 116cm late on Thursday (local time), the third-highest mark for June. That level indicates around 25 per cent of Venice has been flooded.

Venice's sea monitoring agency blamed the unusually high late spring tide on a storm in the Atlantic which brought heavy winds and rain to northern Italy. Another unseasonably high tide is expected on Friday night.

The highest June high tide was registered in 2002, a mark of 121cm, followed by 117cm in June of 2016.

Venice authorities on Friday didn't put out pedestrian bridges, which were usually only used in the peak "acqua alta" season from September to April.

Venice and the rest of the country are still closed to cruise ships but Italy relaxed travel restrictions on Wednesday for Italians and most Europeans.

With AAP.