(BBC) - The Polish government has bought a world-famous art collection, including a rare Leonardo da Vinci painting, for a fraction of its market value
The Czartoryski collection was sold for €100m ($105m; £85m) despite being estimated at about €2bn.
It includes Rembrandt and Renoir works, and Leonardo's Lady with an Ermine.
The head of the Czartoryski family, which owned the collection, said it was a "donation", but the board of its foundation resigned in protest.
The Czartoryski Foundation's management board said it was not consulted about the sale, which was negotiated between Poland's culture ministry and Adam Karol Czartoryski, a descendent of Princess Izabela Czartoryska, who founded the collection in 1802.
Mr Czartoryski, the foundation's head, said he was following his ancestors who "always worked for the Polish nation".
"I felt like making a donation and that's my choice," he said.
The collection is made up of about 86,000 artefacts, as well as 250,000 manuscripts and books. Most of the artworks are housed in the National Museum in the southern city of Krakow.
All are now the property of the Polish state.
The ruling conservative and Eurosceptic Law and Justice party has been pushing to nationalise important businesses and cultural artefacts, as part of a focus on national pride.
Minister of Culture Piotr Glinski said the sale "ensures the right of the Polish nation to the collection".
The collection contains a vast array of artworks, artefacts and historical items including:
* Leonardo da Vinci's Lady with an Ermine
* Rembrandt's Landscape with the Good Samaritan
* Drawings by Renoir
* Manuscripts by the composer Chopin
* Etruscan and Greek vases
* Roman and Egyptian antiquities
* A chair said to come from the house of William Shakespeare
* Armoury with extensive collection of Polish, Islamic and European arms
A notable absence though is Raphael's Portrait of a Young Man, which was looted by the Nazis and remains missing from the collection.
Poland's culture ministry said negotiations for the collection had taken several months.
The Czartoryski Foundation's board of management said it did not oppose selling the collection to the government, but that it was concerned that selling without due diligence - including estimating a fair price - may be against its bylaws, Reuters reported.
Chairman Marian Wolkowski-Wolski told the news agency there was a risk of the collection's eventual dispersal out of public control.
Lady with an Ermine, painted in 1490, is one of only four portraits of women by Leonardo Da Vinci.
It shows Cecilia Gallerani, a young woman in the Milanese court who was mistress to Ludovico Sforza, the Duke of Milan.
His nickname at court was "the white ermine" - explaining the animal's presence in her arms.
Image caption Research shows Leonardo painted Lady with an Ermine in three stages, adding the animal in later versions
It was stolen from Poland by Nazi forces during World War Two, but later repatriated and restored to its owners.
In 2014, new techniques revealed that the painting had been changed at least twice - with the eponymous animal only being added in a later version.