Large parts of Venice were flooded yesterday as heavy rains and strong winds lashed the lagoon city, with sea levels at their highest level in 22 years.

Ferry and water taxi services in the city were suspended and Venice's mayor urged people to stay indoors. Tourists and residents struggled to get across the city over raised walkways.

The Centro Maree, which forecasts water levels, said sea levels in the Adriatic rose 1.56 metres - a level not seen since 1986.

The floods have left people in low-lying parts of Venice, including the popular tourist site of St Mark Square, wading through knee-deep water.

"These are exceptionally high waters," Venice's Mayor Massimo Cacciari was quoted as saying by the Ansa news agency. "Don't venture out unless it is necessary."

The entire city - founded on a collection of marshy islands in the 5th century and criss-crossed by canals - suffers from periodic flooding caused by high tides.

In 2007, the United Nations cultural organisation Unesco warned Venice - a designated World Heritage Site - is under threat from rising sea levels caused by climate change.

It said that unless the problem is tackled, Venice could be flooded daily and water levels would permanently rise by 54 centimetres in the city by the year 2100.

The government has begun a multi-billion euro floodgate project aimed at stopping rising sea levels destroying the city.