Prince Charles, the eldest son and heir to Queen Elizabeth II, is isolating after testing positive for coronavirus for the second time, his office said on Thursday.

"The Prince of Wales has tested positive for COVID-19 and is now self-isolating," said a message on the prince's official Twitter page.

The prince met the Queen in Windsor 2 days before testing positive, according to British media reports.

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But the 95-year-old monarch is not currently displaying any symptoms, an unnamed royal source told the domestic Press Association news agency.

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Buckingham Palace did not say whether the Queen had tested positive or negative for the virus.

Last year the palace was criticized for a lack of transparency before confirming that the Queen had spent a night in hospital for "preliminary" tests, the nature of which have never been specified.

Charles had been due to unveil a statue in Winchester, southern England, on Thursday but his attendance was cancelled at the last minute, leaving him "deeply disappointed", Clarence House said.

The Queen, who isolated in her own "bubble" because of her age at Windsor Castle, west of London, when the pandemic struck in early 2020, has had recent health problems that forced her to take a step back from official duties on medical advice.

However, she is once again filling up her diary as a year of celebrations began this week to mark her record-breaking 70 years on the throne.

The 73-year-old prince first tested positive in March 2020 and subsequently spent around a week isolating at the Queen's Balmoral estate in Scotland.

Charles met several people at a reception in the British Museum on Wednesday, including finance minister Rishi Sunak and interior minister Priti Patel.

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His staff said that the Prince's 2nd bout of coronavirus was discovered after a routine test. He has been fully vaccinated against COVID-19.

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