Visitors to Venice were asked to join police yesterday in the search for an "anti-Christian" vandal who has systematically mutilated holy statues over the past week. "I am raising the alarm," Paolo Costa, the Mayor of Venice, said. "The attacks are becoming more widespread and more frequent." Venice officials said that although the attacks had at first appeared to be random, there was evidence that they formed a planned series of targeted assaults on holy symbols. The attacks began last Sunday night when tourists in St Mark's Square tackled a man in his thirties who took a hammer to marble capitals on the Doge's Palace. The man escaped, leaving a 15th-century capital depicting Moses receiving the tablets badly damaged. Police said the same attacker was presumed to be responsible for damage to statues of St Mark and St Francis at the Church of the Redeemer on the island of Giudecca, erected in 1577-92 to commemorate Venice's salvation from the plague. The damage was found on Monday morning. On Tuesday, a 14th-century bas relief depicting St Peter receiving the keys of Heaven from the infant Jesus in the arms of the Virgin Mary was discovered to have been vandalised. The carving stands outside the church of San Pietro di Castello near the public gardens, site of the Venice Biennale art show. The figure of St Peter had had its hands hacked off and a nearby statuette of the Virgin Mary in a wall niche was smashed. Police said that so far the attacker had hacked off only arms or hands, suggesting some kind of twisted symbolism. La Repubblica said the case was reminiscent of hammer attacks on Michelangelo's Pieta in St Peter's Basilica in Rome in 1972 and on his David in Florence in 1991, both carried out by disturbed individuals. But Paolo Fabbri, a Venice semiologist an expert on signs and symbols said: "Statistically speaking, if you go round Venice hitting things with a hammer the chances are you will hit a Christian symbol. There aren't many African idols in Venice."