'Lost Da Vinci' prompts art row
Art experts have signed a petition to stop drilling into a fresco in Florence's Palazzo Vecchio which may be hiding a Leonardo Da Vinci work.
Around 150 historians from around the world have joined forces claiming it is damaging the existing work, Giorgio Vasari's The Battle of Marciano.
Researcher Maurizio Seracini believes Da Vinci's unfinished The Battle of Anghiari lies beneath on a second wall.
Drilling began last week to allow cameras inside the outer wall.
It is believed Da Vinci started painting his fresco - which is considered by some to be his finest work - in 1504 but abandoned the project because of problems arising from his experimental oil painting technique.
The room was later renovated and Vasari painted his fresco in 1563.
Seracini believes Vasari did not want to destroy Da Vinci's work and instead bricked it up behind a new wall on which he painted.
His theory was stimulated after finding a soldier on Vasari's work holding a small flag bearing the words: "He who seeks, finds."
A radar survey carried out last year revealed a hollow space between Vasari's brick wall and the original stone wall.
Now Seracini, who works at the University of California, and his team are drilling holes in various areas of the fresco and inserting small cameras to capture images inside the covering wall.
Traces of an organic pigment were found, however it will take another two months before lab results are known.
Although the mayor of Florence has said the holes have been drilled in already damaged areas of the fresco, which would be restored after, the intrusive approach has angered scholars.
Cecilia Frosinone, an expert in art restoration who had been working with Seracini on the project, resigned in protest citing "ethical" reasons.
Together with Naples art historian Tomaso Montanari, the pair started the petition appealing to Florence magistrates and the mayor to halt the work.
The petition states they find it "highly unlikely that Vasari has sealed something still legible under a wall", adding that art history research believes the Da Vinci painting to be on the opposite wall to the Vasari.
They have asked officials to stop the drilling until other Renaissance art experts are consulted.