The Dutch government knew of the SS membership of the late Prince Bernhard as early as 1944, according to NRC Handelsblad.More (in Dutch):
The newspaper bases its finding on documents released by the National Archive in The Hague earlier this year. One of the documents refers to a coded telegram, dated September 1944, from Foreign Minister Eelco van Kleffens. The telegram reveals the cabinet knew Prince Bernhard had briefly joined the SS but suspected he had been unable to avoid doing so, "possibly in order to prevent something worse". In the telegram, the foreign minister instructs the Dutch ambassador in the United States not to refute claims, made by American media as of 1941, that Prince Bernhard had been a member of the SS.
Until now, it was not clear if the Dutch cabinet knew such allegations had any basis in fact. For many years Prince Bernhard remained evasive on his links with the Nazi NSDAP party and related organisations. In an interview with De Volkskrant, published shortly after his death in December 2004, the prince admitted to his SS membership for the first time. He always denied having belonged to the NSDAP.