A previously unknown masterpiece by Georgia’s most famous painter has been discovered after its owner tried to sell it to state prosecutors posing as foreign art buyers, according to officials.

The owner of the painting by the primitivist artist Niko Pirosmani was trying to sell it abroad, contravening legislation which forbids the foreign sale of artworks considered to be items of national heritage.

But one of the people involved in the illegal transaction informed the prosecutor’s office, which sent in undercover agents to ensure that the painting, “A Cock, a Brooding Hen and Chickens”, did not leave the country.

Vakhtang Iashvili, the deputy prosecutor of Tbilisi, told a televised news conference that the owner was asking for €363,000 for the painting.

“But the price was reduced to €108,000 during negotia-tions with our agent posing as a foreign buyer,” he said.

The picture, which had been kept in a private collection and was previously unknown to Georgian art historians, has now been handed over to the National Museum.

“It’s a historic day,” deputy culture minister David Tskhadadze said. “The canvas is one of Pirosmani’s best works.”

Pirosmani (1862-1918), whose full name was Niko Pirosmanashvili, was a self-taught Georgian primitivist who was admired by Picasso.

He died in poverty but attracted widespread posthumous acclaim for his charming images of Georgian life and customs, which have since been exhibited in galleries worldwide.