The authorities in the Ukraine on Friday announced the recovery of four of the 24 paintings that were stolen from a gallery in the Netherlands more than a decade ago.
The haul of 16th and 17th century paintings is worth $11 million when stolen from the Westfries Museum in the city of Hoorn in 2005, BBC reported.
The four recovered works had been "in the possession of criminal groups", Ukraine's foreign ministry said.
Vasyl Grytsak, the head of Ukraine's state security service, said the first painting was recovered in early March, followed by a second in early April and two more on Thursday.
"A preliminary examination has determined they are authentic," Grytsak told a press conference.
Reports said they were recovered from Ukrainian ultra-nationalists.
The museum said in December 2015 that two men, reportedly from a Ukrainian nationalist militia, had presented a picture of one of the paintings to the Dutch embassy in Kiev.