Prince Charles will stand in for his 96-year-old mother Queen Elizabeth II at the ceremonial opening of the UK Parliament on Tuesday, Buckingham Palace said.
"The Queen continues to experience episodic mobility problems, and in consultation with her doctors has reluctantly decided that she will not attend the State Opening of Parliament", the palace said in a statement.
"At Her Majesty's request, and with the agreement of the relevant authorities, The Prince of Wales will read the Queen's Speech on Her Majesty's behalf," the palace added.
The Queen's eldest grandson, Prince William, the Duke of Cambridge and next in the line of succession, would also attend the elaborate State Opening of Parliament ceremony, Buckingham Palace said.
The Queen celebrated her 96th birthday on 21 April.
Since the beginning of the year, the monarch has missed several public events due to mobility issues, including the Royal Maundy service, which she skipped for the first time in 52 years. The Queen also underwent a long recovery from a COVID-19 infection after she contracted it in February.
The last time Elizabeth II appeared in public was on 29 March, during the thanksgiving service for her late husband, Prince Philip, Duke of Edinburgh.