Police have discovered 300 paintings in a garden outbuilding owned by a 92-year-old former bricklayer in Poland.

Primarily consisting of Renaissance and German baroque paintings, including one dating back to 1532, the collection was presumably stored in the concrete building since World War II. Many works now suffer condition issues; however, the collection is probably worth in the millions of euros, according to a local art expert.

Police remain baffled as to how the art came to be in the bricklayer's garden. Theories include that they were part of Nazi loot that was left behind 66 years ago, or that the house once belonged to an art dealer.

One artwork has been identified as a lithograph by the Polish artist Jozef Czajkowski, which disappeared from the Silesia Museum in Katowice during the war.

The bricklayer has been charged with handling stolen art, but two strokes have left him unable to communicate.

Interpol is working with the police to unravel the mystery and the collection is now being stored in a museum.