That was one of the findings of a four-year investigation by a consortium of Dutch museums into the origins of works of art now in Dutch museums that may have been stolen from Jewish owners in the Netherlands between 1933 and 1945.
Ekkart declined to comment on the value of the works identified, saying that was not the purpose of the research, but said they clearly included pieces of art "of some value".
"There are objects that have a certain fame so you can imagine that they would command a high value if put on the market," said Siebe Weide, head of the Netherlands Museum Association, when asked how much the items may be worth.
The eight paintings at the Rijksmuseum, one of Europe's largest art collections, included "Portrait of William II, Prince of Orange, as a Child," a 1654 painting by Adriaen Hanneman, and "Portrait of Lord Dubbeldam" by Govert van Slingelandt, dating from 1657.
Gaps in the record of the works' ownership have raised the suspicion that they could have been looted during World War Two or that their original owners, many of them Jewish, may have been forced to sell them, the Netherlands Museum Association.
"The Netherlands has felt a growing urgency over recent years to get clarity over the origins of the public art collections, to do justice to the victims of World War Two," Culture Minister Jet Bussemaker said in a statement.
Heirs of original owners can make a request to a restitution committee which comes under the Culture Ministry but is independent and can make recommendations regarding the ultimate fate of a disputed work.
That could include restoration of the painting to its original owners, or their descendants, or payment of compensation.
About a dozen works have so far been returned, said Willibrord Davids, head of the Restitutions Committee.
The results of the Dutch survey, which began in 2009 and included 162 museums, are being published on a website detailing the uncertainty surrounding the works, which comprise 69 paintings, 24 drawings, two sculptures, 31 pieces of industrial design and 13 Jewish ritual objects.
Some 20 percent of the art in Europe was plundered by the Nazis, according to a 1997 study by the United States National Archives.