The Queen will miss the Commonwealth summit for the first time in 40 years as part of a review of her long-haul travel, Buckingham Palace has announced.
The 87-year-old will be represented at the Commonwealth Heads of Government Meeting (Chogm) in Sri Lanka by the Prince of Wales.
The biennial event, which takes places in November, brings together leaders of the 54 Commonwealth countries.
ITV News Royal Correspondent Tim Ewart reports:
Buckingham Palace denied that the Queen's absence was related to calls for a boycott of the meeting over Sri Lanka's human rights record.
A spokeswoman also stressed that the decision did not mean that the Queen would be "slowing down" in her schedule of public engagements:
The reason is that we are reviewing the amount of long-haul travel that is taken by the Queen.
It is nothing to do with the political situation in Sri Lanka. The key point here is that the Queen will be represented, although she is not there in person, by the Prince of Wales.
The announcement comes after the Queen was admitted to hospital for the first time in a decade in March suffering from the symptoms of gastroenteritis.
The Queen has since resumed her schedule of public appearances including attending the funeral of Baroness Thatcher.
Although the Queen is head of the Commonwealth, it was thought that Charles would not automatically take on the role when he becomes King.