Bell-tower in St Mark's Square, Venice, Italy. (File Photo)

Work began in Venice this week to fit a titanium belt to one of the city's most famous landmarks, the bell-tower in St Mark's Square, Italian News Agency ANSA reported on Thursday.

Experts were called in after a survey revealed the 99-meter bell-tower is sloping by seven centimeters, a sign that its foundations - thousands of wooden posts driven into unstable ground - are failing to provide adequate support.

Surveyors also reckon the foundations of the tower are cracking by a millimeter a year.

To prevent the tower from toppling over, the titanium belt will be wrapped around its foundations two meters below ground and will be invisible from the outside.

Consorzio Venezia Nuova (CVN), the conservation group in charge of the restoration, has warned that the picturesque square - a must on Italy's tourist trail - will be covered in scaffolding for the next two years while the belt is fitted.

Work will also be carried out on the Ducal Palace and the Pontedella Paglia in the square, CVN said.

Affectionately nicknamed El Paron de Casa (The Gaffer), the bell-tower, or "campanile," was first built in 1156-73 on the site of an older tower dating back to around 900 AD.

After suffering structural damage, the tower was rebuilt in the 16th century, but the campanile collapsed completely in 1902.

The much-photographed current tower was built in 1912.

(Xinhua News Agency March 28,2008)