Prince Harry has warned the fight against HIV faces the threat of complacency and called on the next generation to step forward and acknowledge that "stigma and discrimination" are the greatest barriers to defeating the disease.
With people living longer thanks to improved treatment, Aids has "drifted" from the headlines and the fight to combat the virus risks a "real drift of funding and action", Harry told an international conference in South Africa.
Speaking at the Durban summit, where he shared a stage with Aids campaigner Sir Elton John, the Prince added: "When my mother held the hand of a man dying of Aids in an east London hospital, no- one would have imagined that, just over a quarter of a century later, treatment would exist that could see HIV-positive people live full, healthy, loving lives.
"But we now face a new risk - the risk of complacency. As people with HIV live longer, Aids is a topic that has drifted from the headlines. And with that drift of attention, we risk a real drift of funding and of action to beat the virus.
"We cannot lose a sense of urgency, because, despite all the progress we have made, HIV remains among the most pressing and urgent of global challenges - 1.1 million people died of Aids and 2.1 million were infected last year alone.
"HIV remains the number one cause of death amongst adolescents in sub-Saharan Africa. In my own country, infection rates are still rising amongst important groups despite the availability of instant testing and universal access to treatment. So it is time for a new generation of leaders to step forward."
Harry's mother, Diana, Princess of Wales, was the first member of the Royal Family to have contact with a person suffering from HIV/Aids.
In the late 1980s, when many still believed the disease could be contracted through casual contact, she sat on the sickbed of a man with Aids and held his hand.
Both publicly and privately she supported the work of those helping patients, with late-night trips to east London's Mildmay HIV hospice, and serving as patron of the National Aids Trust.
Her son recently announced that he would be dedicating part of his public work to raising awareness about the fight against HIV, and this month he was been publicly tested for the virus - giving a negative result - and held round-table talks with medical experts at an NHS HIV service.
He went on to tell the delegates: "It is time for us to step up to make sure no young person feels any shame in asking for an HIV test. It is time for us to step up to make sure that girls and boys with HIV aren't kept from playing with their friends, classmates, and neighbours.
"It is time for us to step up and acknowledge that stigma and discrimination still act as the greatest barrier to us defeating this disease once and for all."
Harry's charity, Sentebale, already focuses on supporting HIV-positive young people in the African nation of Lesotho and he told delegates he had spent the past few days visiting its new headquarters he opened last summer.
He said during the past decade he had seen "amazing progress" in Lesotho in the treatment of the physical and mental effects of HIV.
The Prince added: "What I believe is that we cannot beat HIV without giving young people in every country the voice they deserve. Without education and without empowerment, HIV will win.
"But just imagine what would happen if, in places like Lesotho and throughout Africa, children were given the tools to protect their health, to speak out against stigma and discrimination, and to support their friends and family.
"In helping young people to fight HIV we would not just be ending this epidemic, we would change the direction of history for an entire generation."