A second-hand dealer has won a case to keep the €4.2m (£3.6m; $4.6m) proceeds from the sale of a rare African mask he found in an elderly French couples attic.

He had been brought In to help clear the attic of the couple, who sold him the mask for €150 (£129; $165).

The couple sued, arguing that they had been misled about the items value.

But the judge disagreed, saying they had failed to appreciate the artworks true worth.

The rare Ngil mask, made by the Fang people of Gabon, is believed to be one of only about 10 in the world.

It would have been worn by members of the Ngil secret society. Historians believe members travelled through villages searching for troublemakers, including suspected sorcerers.

The 19th-Century wooden mask was probably acquired in unknown circumstances around 1917 by René-Victor Edward Maurice Fournier, a French colonial governor and the plaintiffs grandfather.

It was held In the familys possession until it was sold to the dealer. It was later resold at auction to an unknown buyer.

The couple had gone to court to claim a share of the proceeds of the sale, alleging the dealer had misled them about the true value of the mask.

The dealer denied knowing that it was so valuable and said he had demonstrated goodwill by offering the couple €300,000, the masks initial valuation.

His lawyer argued that the couple had failed to research the items true worth before selling it. When youve got such an item at home, you should be a bit more curious before giving it up, Patricia Pijot told French media.

The judge ruled in favour of the dealer and said the couple had failed to exercise due diligence in evaluating the historical and artistic value of the mask.

The offer was retracted after the couple sued.

Frédéric Mansat Jaffré, lawyer for the couple, said: The judge has created a precedent¦ You or I will now need to ask a professional before then going to see another professional.

Gabon had separately requested that the sale of the mask be halted on the grounds that it rightfully belonged to the country. But the court also rejected that argument.

The West African country was a French colony at the time Fournier acquired the mask.

Tens of thousands of works of African art are held outside the continent. Most were removed during the colonial era, sometimes under disputed circumstances.

French President Emmanuel Macron has previously called for the restitution of African art.

I cannot accept that a large part of the cultural heritage of several African countries is in France, he said in 2017. (BBC)