The scandal blew up Friday, a day after Middleton marked an important first as a royal, delivering her first official speech overseas. The well-received speech was delivered to staff and patients at the Hospis Malaysia in Kuala Lumpur and focused on the importance of specialized medical care for seriously ill children. Middleton is a Royal Patron of East Anglia's Children's Hospices in England.
The royal couple were reportedly told about the photos as they ate breakfast Friday before visiting a mosque in Malaysia. A palace source told ABC News that the couple were, at first, simply saddened. But as the day wore on, the sadness turned to shock and anger and, ultimately, resulted in a decision to take legal action against the magazine.
Closer, which featured the photos under the headline, "Oh My God!" defended the decision to publish the photos, saying in a statement on its website that the photos would only appear in the French, not the British edition, and were not degrading.
The prince had expressed his concerns after they were engaged about the paparazzi and said he had given Middleton the chance to get out of the relationship if she thought the attention would overwhelm her.
"I wanted to give her a chance to see in and to back out if she needed to before it all got too much. I'm trying to learn from lessons done in the past and I just wanted to give her the best chance to settle in and to see what happens on the other side," the prince said.
Nude photographs of Prince William's younger brother, Prince Harry, partying in a Las Vegas hotel surfaced online last month and made headlines around the world. In that case, the palace contacted the Press Complaints Commission, which advised British newspapers to not publish the photos.
ABC News' Lauren Sher and Anthony Castellano contributed to this report.