Prince Charles has tested positive for COVID-19, his office said on Thursday, the second time that the heir to the British throne has contracted the disease.
Charles, 73, had been due to attend an event in the southwestern English town of Winchester to mark the 70th anniversary of the accession of his mother Queen Elizabeth and was "deeply disappointed" he could no longer attend, his office, Clarence House, said.
"This morning The Prince of Wales has tested positive for COVID-19 and is now self-isolating," it said in a statement on Twitter.
There was no immediate comment on his condition or when he last saw his 95-year-old mother.
Charles' wife, Camilla, went ahead with engagements in London on Thursday, having tested negative.
On Wednesday, the prince attended a reception for the British Asian Trust where pictures showed him chatting to other guests including British finance minister Rishi Sunak and interior minister Priti Patel.
A spokesperson for Sunak said the minister had tested negative for COVID on Thursday.
Charles, who said in December both he and Camilla had received their COVID-19 vaccine booster shots, previously tested positive for the virus in March 2020 when he said he had been "lucky" to have suffered only mild symptoms.
His son Prince William also contracted COVID-19 shortly after his father in 2020.
During her engagements on Thursday, Camilla said she was "very, very honoured" and "very touched" by Elizabeth publicly stating her desire that she become Queen Consort when Charles becomes king.
Camilla, Charles's second wife, was vilified by the tabloid media after the breakdown of Charles's first marriage to the late Princess Diana, and after her death in 1997.
Coverage has become much more sympathetic in recent years and a poll for the Daily Mail on Wednesday suggested that 55 per cent of the British public now supported her becoming Queen Consort compared to 28 per cent who were opposed.
However, other surveys have indicated that many people still remain hostile to her taking the title, with a YouGov poll in November finding just 14 per cent backed her being queen.