An investigation has been launched into whether the Italian government paid £2.9 million for a figure of Christ on the cross, falsely attributed to Michelangelo.

The 15th century wooden crucifix possibly not by Italian Renaissance artist Michelangelo

The wooden carving was bought a year ago from an art dealer based in Turin, who insisted it was genuine and had been acquired from a Florentine family.

He initially asked for £13 million for the artefact but eventually agreed to accept just under £3 million.

Prosecutors in Rome who specialise in art fraud opened an investigation into the deal this week.

They will scrutinise documents from a court in Lazio, which first started investigating the mystery in the summer after suspicions were raised that the state had wasted its money on a wrongly attributed work.

Great fanfare surrounded the purchase of the wooden figure last December. It was presented to Pope Benedict XVI, exhibited at the Italian parliament and then sent on a tour of the country in an exhibition which attracted thousands of visitors.

There were even plans to lend it to the National Gallery in Washington as a way of honouring President Barack Obama.

But several prominent art experts have said they believe the Christ figure was made by an artist other than Michelangelo.

Francesco Caglioti, an expert on medieval sculptures, told La Repubblica newspaper: "The quality of this work bears no resemblance to those of Michelangelo and every resemblance to the many crucifixes of this kind which were made by artisans in Florence in this period."

Tomaso Montanari, an art history professor at Naples University, said it was "clearly not" a Michelangelo.

A German art historian, Margrit Lisner, said it was probably the work of another Renaissance sculptor, Jacopo Sansovino.

It was first attributed to Michelangelo, after years of scrutiny, by experts from the universities of Florence, Siena and Perugia in 2004.

The director of the Vatican Museums, Antonio Paolucci, said that while there was no cast-iron guarantee that Michelangelo carved the statue, the attribution to the Renaissance genius was based on "very reasonable grounds".