The 2021 Games had been due to begin in Orlando, Florida on Sunday, but were canceled last month as Covid-19 surged in the southern US state.

The Warrior Games "inspired me to create the Invictus Games," a similar multi-national sports event for wounded service members and veterans, said the Duke of Sussex at the virtual event.

Harry, a combat veteran who served two tours in Afghanistan, first attended the US Department of Defense Warrior Games in 2013 in Colorado. He founded the Invictus Games the following year.

"These games are so important," said Harry, speaking from California where he is based with his wife, Meghan Markle.

Regretting he would not be able to support competitors this year at the annual games, he recalled the event was "ultimately the reminder of service both at home and overseas."

"It is about caring for our physical as well as our mental fitness of those that have sacrificed so much," he said.

The wife of US President Joe Biden spoke about the September 11, 2001, attacks on the United States that led to the war in Afghanistan that ended in August 20 years later.

"There was a call to defend the values we hold dear as we waged a global war on terror and a courageous group of men and women stepped forward to say: Me, I will go," she said.

"And that includes you, Harry. You live by a simple principle, served together, recover together," she told the Duke.

"It's a philosophy not limited by the flag, where your brothers and sisters in arms are connected by something so much deeper than the borders that separate us, and you've dedicated your time, talent and heart to lifting up service members from around the globe."

Biden's stepson, the late Beau Biden, was a US army veteran and served one year in Iraq during the war.

The First Lady "has a long history of supporting the adaptive sporting community," the Sunday statement read.

At the virtual event, also attended by US Secretary of Defense Lloyd Austin, she praised the "courage, sacrifice and resilience" of the wounded service members, who trained for months before seeing the Paralympic-style competition cancelled at the last minute.

"By being a part of the Warrior Games, you have not only overcome injuries, both visible and invisible, you show us all that our challenges never have to define us," she concluded.