King Charles III will participate in his annual birthday parade next month from a carriage rather than on horseback, as he battles cancer, British media reported Thursday.

The 75-year-old head of state, who only recently resumed public engagements, will inspect the soldiers taking part in the June 15 Trooping the Colour ceremony from a royal carriage.

The yearly event marks the sovereign's official birthday and is one of the highlights of the royal calendar.

Last year Charles attended his inaugural parade as king on horseback, the first time the monarch had ridden at it since his mother, Queen Elizabeth II, in 1986.

The change for this year's ceremony follows the announcement in February that he had been diagnosed with an unspecified form of cancer.

The king has been receiving treatment and last month royal officials said doctors were "very encouraged" by his progress, allowing him to resume his official duties.

He has been increasingly visible in recent weeks, maintaining a busy public schedule that included attending the Chelsea Flower Show last week.

Next week he will make his first overseas trip since the cancer diagnosis at an event to mark the 80th anniversary of the D-Day landings.

Accompanied by his wife Queen Camilla, 76, and elder son Prince William, 41, the senior royals will be at a commemorative service at the British Normandy Memorial in northern France on June 6.

One notable absentee from those commemorations and potentially the other royal events next month will be William's wife Catherine, 42.

She is receiving chemotherapy treatment for cancer, and was last seen at a public engagement in December last year.

The Press Association said it was unclear if Kate, as she is widely known, would attend the Trooping the Colour ceremony.

Sky News reported Thursday that the Princess of Wales would not return to public duties for the Colonel's Review, another ceremonial military event held the weekend before.

As colonel in chief of the Irish Guards, Kate would usually take a salute at the event.

The British Army initially said in March that she would participate, but swiftly removed the reference to the princess for the review from its website.