Seven people have been arrested by Spanish police on suspicion of involvement in stealing five paintings by Irish-born painter Francis Bacon worth €25m (£19m).
The artworks' owner reported the theft of the paintings and other valuables to the police in July last year, but none of the artworks have yet been recovered.
Investigators in February received information from a British firm which had been asked to verify the provenance of some art.
Photographs of Bacon canvases were included for assessment and these led to the arrest of the suspects.
Bacon often visited Madrid, where he spent time studying Old Master paintings in the Prado Museum, and died there in 1992 at the age of 82.
A statement issued on Saturday did not say when the arrests were made, and the investigation is continuing.