Three people have been arrested in Romania over a £162m art theft from a Rotterdam gallery last October.
Seven paintings by artists including Picasso, Matisse and Monet - swiped from the Kunsthal museum in a late-night raid - have not been recovered, Rotterdam Police said.
Police were alerted to last year's theft by an alarm but arrived at the museum after the thief or thieves had fled.
They launched a major investigation that included interviewing possible witnesses and examining CCTV footage.
At the time, museum director Emily Ansenk, who flew back to Rotterdam after hearing of the theft during a visit to Turkey, said what had happened was "a nightmare for any museum".
The stolen paintings were "unique works that are known around the world," she said.
They include Pablo Picasso's Tete d'Arlequin (1971) and Henri Matisse's La Liseuse and Blanc Et Jaune (1919).
Two pieces by Claude Monet - Waterloo Bridge, London (1901) and Charing Cross Bridge, London (1901) - were also stolen.
The thieves also made off with Paul Gauguin's Femme Devant Une Fenetre Ouverte, Dite La Fiancee (1888), Meyer de Haan's Autoportrait (circa 1889 - 91) and Woman With Eyes Closed (2002) by Lucian Freud.
The museum said the value is "considerable", but declined to put a figure on them.
An expert at the Cornette de Saint-Cyr auction house in Paris, who requested anonymity, said the paintings were worth "between 150 and 200 million euros".