LONDON — King Charles III returned to London from his country retreat on Tuesday for what is expected to be further treatment following his cancer diagnosis.

Charles, 75, and his wife Queen Camilla flew by helicopter to Buckingham Palace from the royals’ Sandringham estate in Norfolk, eastern England. The monarch was seen waving to well-wishers as the couple were driven from the palace to nearby Clarence House.

Royal officials announced last week in a statement that the king was diagnosed with cancer and will suspend public engagements, though he will continue with state business such as signing papers. They did not disclose what form of cancer he has, but said it’s not related to his recent treatment for a benign prostate condition.

King Charles III diagnosedwith cancer following hospitalization for prostate procedure

"The King is grateful to his medical team for their swift intervention, which was made possible thanks to his recent hospital procedure," the statement said. "He remains wholly positive about his treatment and looks forward to returning to full public duty as soon as possible."

The king also said the announcement "helped promote public understanding and shine a light on the work of all those organizations which support cancer patients and their families across the UK and wider world."

The king underwent his first bout of cancer treatment last week. He attended church at Sandringham on Sunday, and thanked the public for the many messages of support he has received.

Prince William returned to royal duties last Wednesday for the first time since his father announced his cancer diagnosis and his wife, Kate, was hospitalized for abdominal surgery. The 41-year-old heir to the throne thanked the public for their "kind messages of support" at a charity gala dinner.

"I'd like to take this opportunity to say thank you for the kind messages of support for Catherine and for my father, especially in recent days," William told the gala dinner for London's Air Ambulance Charity. "It means a great deal to us all."

At the gala, the prince chatted with guests, including "Top Gun" star and U.S. actor Tom Cruise. Earlier in the day, the prince performed an investiture ceremony at Windsor Castle. Queen Camilla, who has been continuing with her royal diary of engagements, said last week that Charles was “extremely well under the circumstances.”

Contributing: Danica Kirka