A message on his official Twitter page said Charles tested positive on Thursday morning UK time and was "deeply disappointed" not to be able to attend a scheduled visit in the city of Winchester in southern 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.
Charles previously contracted the coronavirus in March 2020, during the first wave of the pandemic. Officials said he had mild Covid-19 symptoms then, and Charles said later that Charles and Camilla isolated in Scotland at the time.
Britain's Press Association news agency reported that Charles recently met with his mother, Queen Elizabeth II, but the monarch was not displaying any symptoms.
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, visiting a sexual assault referral center in London.
Spain's King Felipe VI, 54, and Denmark's Queen Margrethe II, 81, also tested positive for the coronavirus this week.
- AP
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