COPENHAGEN, Denmark (AP) — Prince Joachim, the youngest son of Queen Margrethe of Denmark, has undergone emergency surgery for a blood clot in his brain, the royal palace said.

The 51-year-old prince, who had been on vacation in France, was admitted to the Toulouse University Hospital late on Friday and was immediately operated on. The palace said he is in a stable condition and that his French-born wife is by his side.

Joachim married Marie Cavallier, with whom he has two children, in 2008, and she became Princess Marie. He also has two children from his first marriage to Hong-Kong born Alexa...