Queen Elizabeth II is set to open the Commonwealth heads of government meeting on the Mediterranean island of Malta.
The summit is expected to deal with climate change, the threat of extremist violence and other issues.
The 89-year-old British monarch will briefly address the other leaders of the 53-nation organisation Friday. She is accompanied by her husband Prince Philip and her son Prince Charles, heir to the throne.
The Commonwealth links more than 2 billion people on five continents, including large countries like India and Australia and small island states like Tonga and Vanuatu.
British Prime Minister David Cameron has announced plans to set up a Commonwealth unit targeting the extremist “scourge” fuelling international terrorism.
The Commonwealth summit is held every two years.
