The three children of British heir-to-the-throne Prince William and his wife Kate have released a Father’s Day message and photograph on Sunday, saying “We love you, Papa”.

The photo shows the three children, Prince George, 10, Princess Charlotte, nine, and Prince Louis, six, hugging William on a beach, with the photograph taken from behind as they all look out to sea.

The caption says the photo was taken by the princess – reportedly in Norfolk earlier in June – and reads: “We love you, Papa. Happy Father’s Day”.

It is signed with the three children’s initials – the first time they have appeared on the Wales family’s social media.

The photograph was released a day after Kate, Britain’s Princess of Wales, was seen in public for the first time since she revealed she was undergoing treatment for cancer.

Kate, William and the children joined the King and other members of the royal family on the balcony of Buckingham Palace on Saturday after watching a military parade to celebrate the monarch’s official birthday.

The princess, 42, spent two weeks in hospital in January after she had major abdominal surgery.

Two months later she announced in a video message that tests had revealed the presence of cancer and she was receiving preventative chemotherapy.

She is still having treatment, but she said on Friday that she was able to attend the Trooping the Colour because she was making good progress. However, she noted that she was “not out of the woods” yet.

In a separate post on X on Sunday, Kate and William paid tribute to the King for Father’s Day, sharing a photograph of William as a child playing football with his father.

-with AAP