Prince Harry has said the fight against HIV cannot be won unless children living with the disease are given a voice.
Commenting ahead of a polo match in aid of his Sentebale charity, Harry also said he continued to support the world's commitment to ending the Aids epidemic by 2030.
Harry hopes to raise a million pounds from the event being staged in Singapore for his organisation's work with HIV positive children in Lesotho and Botswana as well as other projects helping vulnerable youngsters.
Before the polo match begins later, when a Sentebale team led by the prince takes on opponents captained by a professional player, a minute's silence will be held for the victims of the London terrorist attack.
Writing in the official programme for the Sentebale Polo Cup, with his charity co-founder Prince Seeiso of Lesotho, the prince said: "In the past year we have expanded operations into Botswana, addressing the pressing needs of the country with the world's third-highest HIV prevalence.
"We will continue to support the global commitment to ending the Aids epidemic by 2030.
"We believe that we cannot beat HIV without giving children and adolescents the voice they deserve.
"It is our ambition to change the tide of this epidemic by ensuring more young people know their status, access treatment and are empowered to tackle stigma and play their part in bringing the Aids epidemic to an end."
In-roads have been made in tackling the Aids epidemic among adults and the under-fives in Africa but it is still the biggest killer of the continent's adolescents.
They face problems with accessing treatment, as clinics are sometimes only open during school hours, stigmatisation is still prevalent and the language used by adults helping them can be off-putting.
Sentebale launched its Let Youth Lead campaign in April to give young people with HIV a platform to tell decision makers, NGOs, governments and others what they need, and the charity has already held two summits to train up young advocates.
The polo match is being staged at the exclusive Singapore Polo Club, founded in 1886 by British officers.
Among the guests were Karen Gillan, a former Doctor Who companion currently starring on the big screen in Guardians Of The Galaxy Vol 2, actress Gemma Chan, who is reportedly dating comic Jack Whitehall, and Downton Abbey actress Joanne Froggatt.
Harry arrived in a smart casual outfit of jacket and trousers and a shirt without a tie, and was greeted by Sentebale chief executive Cathy Ferrier and Nacho Figueras, a professional polo player and Sentebale ambassador.