King Charles has revealed he was reduced to tears by the messages and cards of support he has received since his cancer diagnosis, as he returned to work on Wednesday.

The king carried out his first face-to-face official duties – an audience with the prime minister and a privy council – since his medical condition was made public.

The monarch met Rishi Sunak at Buckingham Palace late on Wednesday afternoon, marking the restart of their weekly encounters to discuss matters of government.

Beforehand, Charles held an in-person privy council at the royal residence, where attenders included the lord president of the council, Penny Mordaunt, and a selection of other ministers who are privy counsellors.

It is the first time the 75-year-old king, who was pictured with Sunak, has been filmed carrying out official duties since his shock diagnosis.

Sunak told the monarch that it was “wonderful to see you looking so well”, prompting Charles to joke it was “all done with mirrors”.

Sunak added: “We’re all behind you. The country is behind you.”

Charles replied: “I’ve had so many wonderful messages and cards. It’s reduced me to tears most of time.”

The king, who has been dealing with his red boxes of state papers behind the scenes, started outpatient treatment for an undisclosed form of cancer just over two weeks ago.

Charles, who only acceded to the throne 17 months ago, has had a difficult start to 2024, beginning with a three-night hospital stay for a procedure on an enlarged prostate, during which time his cancer – not prostate cancer – was discovered.

Meanwhile, his daughter-in-law the Princess of Wales is recovering after major abdominal surgery, but is not expected to be back on official duties until after Easter.