A 400-year-old painting that might have been executed by Italian master Michelangelo Merisi da Caravaggio has been found in an attic in southern France.

Eric Turquin, the French expert who retrieved the painting two years ago, says it is in an exceptional state of conservation and estimates its value at 120 million euros (about £100m).

The picture, whose authenticity has not been established, had been left for more than 150 years in a property in the outskirts of Toulouse.

A 400-year-old painting (above) that might have been executed by Italian master Michelangelo Merisi da Caravaggio has been found in an attic in southern France

Eric Turquin, an art expert in Paris, said the unidentified Toulouse family were investigating water damage and needed to access a roof. He said: 'They broke a door which they did not have a key to,' said Mr Turquin. 'Behind the door was a painting that the owners did not know about'

Called 'Judith Beheading Holofernes,' it depicts the biblical heroine Judith beheading an Assyrian general, and is thought to have been painted in Rome circa 1604-05.

Judith, a widow, was said to have seduced Holofernes before getting him drunk and killing him with his own sword.

Typically for a Caravaggio painting, it is the moment of the greatest dramatic impact - the decapitation itself - that it depicted.

Fitting with his mastery of light and shadow, which the Italian developed into a technique known as chiaroscuro, the painting is dramatically lit from the side to emphasise the facial expressions of the murderer and her maid, Abra.

Mr Turquin told a press conference today that there 'will never be a consensus' about the name of the artist.

'Export of the painting has now been banned, and every effort is being made to confirm its precise origin,' said a culture ministry spokesman.

The ministry's official website meanwhile says: 'The painting deserves to be kept on French territory as a very important landmark Caravaggio painting.'

The painting could be worth more than 100 million euros has been found in an attic in Southern France

The picture, whose authenticity has not been established, had been left for more than 150 years in a property in the outskirts of Toulouse

Eric Turquin, an art expert in Paris, said the unidentified Toulouse family were investigating water damage and needed to access a roof.

'They broke a door which they did not have a key to,' said Mr Turquin. 'Behind the door was a painting that the owners did not know about.'

He said that one of the family's ancestors – a soldier – had probably acquired the masterpiece while fighting abroad with Napoleon Bonaparte.

Mr Turquin said the painting was so gory that the officer's wife probably asked for it to be removed from her sight.

Caravaggio painted two versions of Judith Beaheading Holofernes, one of which is on display at the National Gallery of Ancient Art in Rome.

The other disappeared without trace around 100 years later, and would now be worth at least 100 million pounds.

The Louvre Museum in Paris is now among world famous art institutions considering making an offer for the painting.

Caravaggio was born in Milan in 1571, and became one of the great Baroque painters, working mainly in Rome, Naples, Malta and Sicily.