TOURNAI, BELGIUM - The demolition of a historic bridge across a Belgian river is triggering fears among residents of Tournai that the city symbol will be disfigured permanently when a new span replaces it.

The authorities insist they chose the most cost-effective option to build a new crossing that will allow larger barges to sail underneath while preserving the character of the medieval monument, known locally as the "bridge of holes".

Workers pressed ahead on Friday with demolishing the arches which were rebuilt after World War II when British troops blew up the original span, along with Tournai's other bridges, to slow the Nazi invasion of Belgium in May 1940.

Charles Deligne, curator of the city's military museum, confessed he felt "some anger" after the authorities rejected plans for a bypass canal and began demolishing the bridge a week ago.

"I am also enormously disappointed because we missed a great opportunity," Deligne said, wistfully recalling the beauty of the bridge that appears in a pre-war photograph in his museum.

"The bypass option would have been a very beautiful option," he added.

Deligne warned the middle of the three arches in the new version would be so high as to vastly alter the medieval style that was largely retained in the post-war reconstruction.

The two fortified stone towers on either side of the river are more or less the same as they were when first built in the 14th century.

Christophe Van Muysen, the project's inspector for the French-speaking Wallonia region, played down the way the bridge over the Scheldt river will look in the future.

"It will have the same medieval appearance, but the arch will be bigger geometrically," Van Muysen told AFP as a crane's maw and drill demolished the arches, debris splashing into the water. -AFP