LONDON  - Britain's Prince William said on Friday his wife Kate was "doing well" in a rare public comment about the Princess of Wales as she undergoes preventative chemotherapy for cancer.

Kate announced in March she was having treatment after cancer was found following abdominal surgery she underwent at the start of the year.

She said at the time she was well, but the couple's office have said they would not be providing regular updates on her health and she is not due to return to public duties until her doctors say she is well enough to do so.

However, asked how his wife was faring during a visit to a community hospital on the Isles of Scilly off the coast of Cornwall in southwest England, William, 41, replied: "She's doing well, thank you, yes."

The heir to the throne, who is also the Duke of Cornwall, was on a two-day trip to the region, where he saw a site for a new project to tackle homelessness, spent time on a beach with local groups and visited a community hospital.

He arrived by boat on Friday on the Isles of Scilly, 28 miles (17 miles) off the coast of Cornwall, buying a Cornish pasty, the region's famous savoury pastry and telling crowds who had gathered on the quayside that his family were "very upset" that he was there without them.

William had also met harbour operators and local business people on St Mary's, the largest of the islands, talking to them about their preparations for the summer tourist season.

His father King Charles, 75, had also been out and about on Thursday, visiting a military training college, in his latest engagement since he returned to public duties after his cancer diagnosis.

(Reporting by Sarah Young; Editing by Alex Richardson)