Prince William has delivered a surprise message to the family of Steve Irwin at a glittering event for their environmental charity.

The Prince of Wales was full of praise for the late environmentalist in a video message to the Steve Irwin Gala in Las Vegas at the weekend.

“Tonight is all about conservation and continuing Steve’s global mission to protect life on our planet,” William said.

“His dream was to have the cleanest water, the freshest air and wildlife in abundance. But most of all, he wanted a future for our children.”

Irwin died in 2006, aged 44, after being stung by a stingray.

The video message was released on Sunday by Wildlife Warriors, the charity Irwin and wife Terri set up in 2002 to aid animal conservation.

It is still run by Terri, with the couple’s daughter Bindi now also on board.

“Advocating for the preservation of life on our planet … is a passion I share,” Prince William said.

“It is why I launched the Earthshot Prize, to search for and scale the most innovative solutions to the world’s greatest environmental challenges. Our mission is to protect and restore our planet in this critical decade leading up to 2030.”

The Earthshot Prize awards £1 million ($1.9 million) to five winners in environmentalism each year.

The prince said he was “hugely grateful” to the Irwins for their work.

“I’m proud to join you virtually tonight to celebrate their work through Wildlife Warriors,” he said.

“Seeing the global impact of the charity, founded by Steve and Terri in 2002, brings hope for the future. Never before has it been so important for every single one of us to make environmentally conscious choices that will ensure the healthy future of our planet.”

The video message is yet another step in William’s return to royal duties as his wife, Kate, continues her preventative chemotherapy for cancer.

Out and about on a royal visit to Cornwall last week, the prince was asked how Kate was faring.

“She’s doing well, thank you, yes,” he said.

It is one of only a handful of updates on the Princess of Wales’ health since her video message to reveal her cancer treatment.

Kate has been out of the public limelight since having major abdominal surgery in January.

When she announced her cancer in March, she said she was well, but Kensington Palace has said it will not provide regular updates on her health.

The princess will not return to public duties until her doctors say she is well enough to do so. So far, there has been no firm date.

William, who is also the Duke of Cornwall, made a two-day trip to the region in south-west England last week.

He saw a site for a project to tackle homelessness, spent time on a beach with local groups and visited a community hospital.

He arrived by boat on Friday on the Isles of Scilly, 27 kilometres off the coast of Cornwall, buying a Cornish pasty, the region’s famous savoury pastry and telling crowds who had gathered on the quayside that his family were “very upset” that he was there without them.

Prince George, 10, Princess Charlotte, nine, and Prince Louis, six, were “very jealous that I’m here and that they’re not here as well”, William said.

He also met harbour operators and local business people on St Mary’s, the largest of the islands, talking to them about their preparations for the summer tourist season.

-with AAP