The revelation, a sensitive one for a country still wrestling with the legacy of World War II, comes in the newly released diaries of her foreign minister Eelco van Kleffens, Trouw newspaper said.
The queen acted because she feared that Leopold III, who was being held by the Nazis in Austria, would be killed, according to the book “Your Majesty, You Do Not Know Real Life”.
Despite being “anti-papist and anti-German”, queen Wilhelmina asked van Kleffens in March 1945 to “sound out” a possible swap with senior Nazis.
But she was ready to do the deal to help a fellow member of a royal family, Trouw reported.
Wilhelmina was living in exile at the time following the German invasion of the Netherlands in 1940. She abdicated for health reasons in 1948 and died in 1962.
She decided to take action after a conversation with the Belgian Queen Mother Elisabeth in Brussels who feared that her son and his family would be “liquidated”, Trouw reported.
The Belgian royal family was eventually freed by US troops in May 1945. Some Belgians opposed Leopold III's return home after he was accused of pro-German sympathies. He moved to Switzerland after the war and abdicated in favour of his son Baudouin in 1951.
The Netherlands suffered bitterly under the Nazi occupation, but in recent years has had to come to terms with its failure to prevent — and in some cases with its complicity in — the extermination of around 110,000 of its pre-wartime population of 140,000 Jews.
Perhaps the best known was the diarist Anne Frank, who hid in an Amsterdam house from the Nazis before being betrayed and sent to the Bergen-Belsen, where she died in 1945.