ROME - More than 300 scholars have signed a petition to Florence's mayor and that city's top art authority to stop a project that hopes to find a Leonardo da Vinci masterpiece behind a fresco by Giorgio Vasari in the Palazzo Vecchio, now city hall.The Leonardo fresco, commissioned by the Republic of Florence around 1503, depicted a battle between Milanese and Florentine forces that had occurred about 60 years earlier in Anghiari, a Tuscan town. Today a less brutal, but perhaps no less bitter, war is brewing between art historians and proponents of the project, led by the National Geographic Society and the Center of Interdisciplinary Science for Art, Architecture and Archaeology at the University of California, San Diego. Project leaders have bored holes into the Vasari work so that an endoscopic probe can examine the wall behind it for any trace of the Leonardo fresco. On Monday an Italian heritage conservation group complained to Florentine prosecutors, and an investigation has been opened. "Our constitution guarantees the protection of Italy's cultural heritage, and now it will be up to the law to determine whether damage has been done here," said Alessandra Mottola Molfino, president of the heritage conservancy Italia Nostra, who dismissed the search for the lost Leonardo as a publicity stunt rather than a scientific endeavor. "We've grown weary of using art history as an event or a marketing opportunity," she said. In times of belt tightening and with hundreds of Italian monuments requiring restoration, she added, there were more fruitful ways to sponsor culture. "It's like a scratch-and-win lottery ticket," said Tomaso Montanari, a professor at the University of Naples, who has been circulating the petition, pointing out that scholarship has not determined the precise location of Leonardo's fresco. Many art historians doubt that the fresco still exists in situ at all because Vasari, one of Leonardo's greatest admirers, would have made every attempt to salvage "The Battle of Anghiari" rather than paint over it. Mr. Montanari and other art historians have called on the culture ministry to establish a committee of Renaissance art experts that would further study the hall in the Palazzo Vecchio before new tests are carried out."Conservators are paid to preserve works of art, not destroy them," Mr. Montanari said. "We need to be sure that these scientific guarantees are upheld."But Alexander Moen, vice president for mission programs at the National Geographic Society, noted that the project's leader, Maurizio Seracini, an engineer and director of the interdisciplinary center in San Diego, had received approval from city and state art authorities for his examination, and was working with restorers from the Opificio delle Pietre Dure, one of the most respected restoration institutions in Italy."It's not like we indiscriminately made holes on Vasari's frescoes," he said. "We are confident in the approach that was taken, which was deliberate and not decided on alone but with the critical agencies that are stakeholders."National Geographic began supporting Mr. Seracini's project four years ago. Mr. Moen said that after an initial investment of 250,000 paid to the City of Florence in exchange for the right to publish the results, the costs keep increasing, though he declined to comment on the final tally. National Geographic plans to present television and magazine specials about the project next year. The first of six holes, just large enough to permit the entry of a four-millimeter endoscopic probe, was made on Nov. 27, and the final one was drilled this week. "We found a probe with a miniscule tip and ensured that the drilling was done in places on the fresco that had already been damaged and had no original paint on them," said Marco Ciatti, one of the restorers. Opponents of the project had little to fear, he said, adding, the "culture ministry would never authorize anything that could damage the frescoes."As further endoscopic exams are carried out during the next few weeks, material gathered from the cavity behind the wall will be examined in a lab for evidence of the Leonardo fresco. But other restorers have bristled at having to work on a project that they believe is short on scientific data. Cecilia Frosinini, Mr. Ciatti's colleague at the Opificio, refused to participate, an act of rebellion that kick-started the petition. "You can't ask me to work on something that is going to have a significant impact without being given any background research to study," she said. "I took an ethical position and refused."There is also debate over what would happen should Mr. Seracini find traces of some other painting. "What are we going to do - tear down Vasari's wall?" asked Chiara Silla, who was director of the Palazzo Vecchio for nine years, during which Mr. Seracini conducted some of his studies. "The message that's coming across is that this is a city that doesn't protect its artwork."Keith Christiansen, curator of European paintings at the Metropolitan Museum of Art, said by e-mail, "This is just plain a bad idea at the wrong time and it would not be proposed were it not that Leonardo has become a supercelebrity." Still, the mayor of Florence, Matteo Renzi, remains a firm champion of the project. "I can't tell you what we've found, but we're very satisfied," said Mr. Renzi, a media-savvy rising star in Italian politics. "The scientific community might do well to wait for the results before complaining." If Leonardo's painting were found, it would revolutionize Renaissance art, he said. "Only a crazy person would stop now. I think Florence has the right to solve one of the greatest mysteries of the history of art."