Police in Serbia have recovered a painting by French artist Paul Cezanne that was stolen at gunpoint from a Swiss museum four years ago, officials say.
Four men, including the leader of the gang that conducted the robbery, have been arrested in the capital, Belgrade, and the town of Cacak.
Cezanne's Boy in a Red Waistcoat, which media said was worth more than $100m, was one of four paintings stolen from the E G Buehrle Collection in Zurich in 2008 by a trio of masked robbers who burst in just before closing time and told staff to lie on the floor while they took what they wanted.
A Swiss expert authenticated the oil on canvas painting retrieved by police, hidden in the door panel of a car.
Serbian Interior Minister Ivica Dacic said the police raids, planned since 2010, took place when the suspected robbers decided to take the Cezanne painting to a wealthy Serb who agreed to buy it for $4.6m.
Dacic said nearly $2m in cash and firearms were found with the four arrested men.
He said one of the arrested men was the leader of the gang that conducted the robbery, while the three others are believed to be accomplices in the crime.
"I think this is really an impressive action conducted jointly with Swiss police,'' Miljko Radisavljevic, the special prosecutor for organised crime, said.
Art experts have suggested the robbers took advantage of low security at the Swiss museum without knowing about the paintings or how difficult it can be to sell such well-known stolen art works.