The bust of Egyptian Queen Nefertiti, considered to be the Mona Lisa of the ancient world, may be a fake, according to two art experts.

Swiss historian Henri Stierlin, author of several books on Egypt and the Middle East, claims in his new work, Le Buste de Nefertiti – une Imposture de l'Egyptologie? (The Bust of Nefertiti – an Egyptology Fraud?) that the treasure, until now believed to be 3,300 years old, could be a 1912 copy.

He suggests it was made by an artist named Gerardt Marks on the orders of German archeologist Ludwig Borchardt, who is credited with digging it out of the banks of the Nile south of Cairo in 1912.

"It seems increasingly improbable that the bust is an original," Stierlin, who has been working on the subject for 25 years, told Agence France-Press.

He said Borchardt had hoped to produce a new likeness of the 18th-dynasty Egyptian queen wearing a necklace he knew she had owned, and at the same time carry out a colour test with ancient pigments found at the archeological site.

But Stierlin said a German prince admired the copy as an original, and Borchardt didn't want to make his guest look stupid.

Recent radiological tests seemed to have proven that the bust was more than 3,000 years old. They also uncovered a hidden face carved into the statue's limestone core.

But Stierlin has argued that while is it possible to carbon-date pigments, it is impossible to accurately date the bust because it is made of stone covered in plaster.

Inconsistent with Egyptian style

He noted that the bust has no left eye, which the ancient Egyptians would have considered a sign of disrespect to their queen. He pointed out that the shoulders were cut vertically, while Egyptian artisans cut their busts' shoulders horizontally.

And he said French archeologists who were present at the 1912 dig never mentioned the find, nor did contemporary written accounts.

Berlin author and historian Edrogan Ercivan's new book, Missing Link in Archaeology, which was published last week, adds to Stierlin's argument. Ercivan has also called the Nefertiti bust a fake, saying it was modelled on Borchardt's wife, the Guardian newspaper reported.

Both historians have said Borchardt kept the bust for 11 years before handing it over to a Berlin museum.

Dietrich Wildung, director of Berlin's Egyptian Museum, has refuted the historians' claims, saying they are attempts to exploit the work's popularity. "A beautiful woman and a putative scandal — that always sells," he told the Guardian.

The bust is now on display at Berlin's Altes Museum. It will return to the Neues Museum when it reopens in October after a restoration by British architect David Chipperfield.

Queen Nefertiti, the wife of Pharaoh Akhenaten, lived from about 1370 BC to 1330 BC.