Coronation portrait of UK's King Charles unveiled

The official coronation portrait of Britain's King Charles was made public on Tuesday, two years after he was crowned, in a tradition dating back more than 400 years to a time when such a painting often became the defining image of a monarch.

The portrait of Charles, in his Robe of State standing beside the Imperial State Crown, and one of his wife, Queen Camilla, will go on display in London's National Gallery for a month before being moved to Buckingham Palace, their permanent home, Buckingham Palace said in a statement on Tuesday.

Charles, 76, who was diagnosed with an unspecified form of cancer early last year some 10 months after his coronation, has been sitting for the portrait while he undergoes treatment.

The king and queen commissioned the paintings shortly after the coronation ceremony at London's Westminster Abbey, choosing different artists. Charles was painted by Peter Kuhfeld, while Camilla selected Paul Benney, Buckingham Palace said.

"I have tried to produce a painting that is both human and regal, continuing the tradition of royal portraiture," Kuhfeld said in a statement of the image of the king whose backdrop is the Throne Room in St James's Palace.

Camilla is seen wearing her Coronation Dress of ivory coloured silk, next to a different crown. Benney said he wanted to acknowledge the historic nature of the coronation while also showing "the humanity and empathy of such an extraordinary person taking on an extraordinary role".

Historically, the paintings were used as a show of power. The earliest example in the royal collection is the state portrait of James I of England, James VI of Scotland, from 1620.