A message on his official Twitter page said Charles tested positive on Thursday morning and was ``deeply disappointed'' not to be able to attend a scheduled visit in Winchester, England.

Charles, 73, met dozens of people during a large reception at London's British Museum on Wednesday evening. He was accompanied by his wife Camilla, and was in close contact with Britain's Treasury chief Rishi Sunak, among others.

Charles' office, Clarence House, confirmed that he is triple vaccinated.

It was not immediately clear what his condition was or whether Charles had recently met with his mother, Queen Elizabeth II.

The queen, 95, marked her Platinum Jubilee on Sunday by expressing her wish for Camilla to be known as Queen Consort when Charles becomes king.

Camilla carried on with her engagements as scheduled on Thursday, visiting a sexual assault referral centre in London.

Charles previously contracted the coronavirus in March 2020, during the first wave of the pandemic. Officials said he had mild COVID-19 symptoms then. Charles and Camilla were isolated at Queen Elizabeth II's Balmoral estate in Scotland at the time.

Spain's King Felipe VI, 54, and Denmark's Queen Margrethe II, 81, also tested positive for the coronavirus this week.