Two paintings by impressionist master Pierre-Auguste Renoir, stolen from a museum in southern France and later discovered hidden behind a wall, have sustained slight damage, prosecutors said on Monday.

Thieves last month broke into the museum in the southern town of Cagnes-sur-Mer and escaped with two works by Renoir, abandoning two others as they fled.

Suspects behind the theft were arrested last week as authorities discovered they were next planning to target the Fondation Maeght in Saint-Paul-de-Vence, home to one of Europe's largest collections of modern art.

On Friday, authorities announced that the two missing stolen works valued at 4.2 million euros ($4.7 million) had been found.

They were a painting titled "Portrait of Madame Colonna Romano" and a depiction of a woman at a well called "Young Woman at the Well".

Marseille prosecutor Nicolas Bessone told reporters in Paris that the paintings were recovered on Thursday during a search of a home in the southern town of Clermont-l'Herault.

The discovery of the stolen works followed the arrest of six people, including a woman, on Wednesday, said Bessone.

Their arrests were brought forward after the main suspect carried out a reconnaissance visit to the Fondation Maeght.

"We were very clearly looking at the repetition of a criminal scheme," said the head of the Alpes-Maritimes judicial police, Eric Antonetti.

The two key suspects include a 29-year-old, who was charged after investigators recovered DNA from a bag left behind during the getaway.

He had been under investigation for drug trafficking, said the head of France's national judicial police, Christian Sainte.

'Completely undetectable'
The paintings were hidden behind a solid cinder-block wall and concealed so well that they were discovered only during a second search.

"They were completely undetectable," Bessone said.

Police returned to the place after securing a confession.

"During the initial search, we had examined the walls, checking for hollow spaces," said Sainte.

The two paintings were "in relatively good condition", although "the two works showed signs of damage," Bessone said.

The frame of "Young Woman at the Well" was slightly damaged, while "the canvas of 'Portrait of Madame Colonna Romano' had a tear," Bessone said.

The tear was located "on the dress" in the portrait, the prosecutor said, adding both paintings "will require restoration work".

The suspects appear to have acted without a buyer or sponsor, said Antonetti.

The paintings were found hidden in the home of one of the suspects in Clermont-l'Herault.

The four men under formal investigation are aged between 29 and 51, and three of them have previous criminal convictions. Two of them remain in custody.

Culture Minister Catherine Pegard praised "the efficiency and determination of all those who made this outcome possible."

"Their commitment made it possible to recover these works in record time," the culture ministry said.

A spate of heists at French museums -- including at the Louvre -- has highlighted inadequate security in some cases and led to questions about whether criminal gangs see them as soft targets.

Crown jewels valued at around $100 million were stolen in broad daylight from the Louvre in Paris last year.

While the four suspected Louvre robbers have been arrested, the jewels they are accused of grabbing in the seven-minute heist have still not been found.