Britain's Prince Harry in Las Vegas to present NFL award

Harry presenting NFL player Cameron Heyward during the NFL Honours award show in Las Vegas (David J Phillip/AP)

Britain's Prince Harry has appeared at the NFL Honours in Las Vegas to present an award, just days after King Charles revealed his cancer diagnosis.

Harry appeared at the event to present Pittsburgh Steelers defensive lineman Cam Heyward with the Walter Payton Man of the Year Award.

It comes after Harry flew thousands of miles from his Californian home to be at Charles' side on Tuesday, meeting with his father for around 45 minutes at Clarence House.

The duke at the NFL Honours in Las Vegas (David J Phillip, AP)

There was no meeting between William and Harry, who have had a fractured relationship for a number of years, exacerbated after Harry and Meghan stepped down as working royals, moved to America and aired a string of grievances against the royal family.

Harry appeared in public for the first time since his father’s diagnosis on Thursday night and while introducing the award joked that the United States “stole rugby from us and you made it your own”.

“Instead of passing it backwards, just pass it forwards,” he said. “Why not wear pads and a helmet?

“All kidding aside, what you guys do on and off the field is truly remarkable. You are role models for millions in the way you carry yourselves and the way you give back.

“This final award, the highest honour, is all about serving your community, and there is one special man we’d like to pay tribute to now.”

When Heyward received the award, he hugged Harry, before he said: “Prince freakin’ Harry, I’m just shocked, that’s Prince Harry.”

The award recognises a player who has achieved on and off the field and made a positive impact on their community.

The winner is awarded $250,000 to donate to a charity of their choice.