The Queen has been caught on audio voicing her displeasure at “irritating” leaders who have refused to confirm their attendance at an upcoming global climate summit.

Her Majesty was caught expressing a rare political opinion to her daughter-in-law Camilla, the Duchess of Cornwall, and Welsh politician Elin Jones on Thursday (British time).

“Extraordinary, isn’t it?” the Queen says.

“I’ve been hearing all about COP. [We] still don’t know who is coming, no idea. We only know about people who are not coming and it’s really irritating when they talk, but they don’t do.”

Prime Minister Scott Morrison confirmed only on Friday afternoon that he would attend the COP26 summit in Glasgow on October 31, after earlier signalling he might skip it. Others yet to say they will be there include Chinese President Xi Jinping of China, Russian President Vladimir Putin and Brazilian President Jair Bolsanaro.

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“Exactly. It’s a time for doing,” Ms Jones responds.

“And watching your grandson [Prince William] on the television this morning saying there’s no point going to space, we need to save the Earth.”

“Yes, I read about it,” Her Majesty replied.

Russell Myers, the royal editor for British tabloid The Mirror, said the monarch’s comments were “a thinly veiled swipe at world leaders including Scott Morrison”.

“It is clear as day who she is talking about,” he told Nine’s Today show on Friday.

“Scott Morrison has not committed to going to this huge UN climate change conference. Prince Charles was imploring him to do so [this week]. It is a really big deal. We have got to get people around the table.

“If you don’t have the world leaders there, especially the big hitters, then what’s it all for really? Certainly the Queen would implore Scott Morrison to go, as I am sure other world leaders attending would do as well.”

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The Queen’s rare public comments came after her grandson, Prince William, told the BBC on Thursday that the world’s greatest brains should be focused on solving the environmental problems facing the Earth.

William appeared to criticise Jeff Bezos, the world’s richest person, Elon Musk and Briton Richard Branson, whose rival ventures are all vying to usher in a new era of private commercial space travel.

“We need some of the world’s greatest brains and minds fixed on trying to repair this planet, not trying to find the next place to go and live,” the Duke of Cambridge said of the space race.

Mr Musk has spoken about missions to Mars, and has Mr Bezos described his inaugural space flight in July as part of building a road to space “so that our kids and their kids can build a future”.

“We need to do that to solve the problems here on Earth,” said Mr Bezos, who on Wednesday celebrated sending Star Trek actor William Shatner into space in his New Shepard spacecraft.

Speaking out on green issues has become a major feature of the British royal family, and William, 39, is following in the footsteps of his late grandfather Prince Philip, the Queen’s husband, and his father, Prince Charles.

Charles, the 72-year-old heir to the throne, has for decades called for action to stop climate change and environmental damage, long before the issue became mainstream, often facing ridicule along the way.

“It’s been a hard road for him. He’s had a really rough ride on that, and I think he’s been proven to being well ahead of the curve,” William said.

“But it shouldn’t be that there’s a third generation now coming along having to ramp it up even more. For me, it would be an absolute disaster if George [his eldest child] is sat here … in like 30 years’ time whatever, still saying the same thing, because by then we will be too late.”

In an echo of his father’s message earlier this week and the Queen’s own remarks, William said the upcoming COP26 summit had to deliver.

“We can’t have more clever speak, clever words but not enough action,” William said.

The prince’s personal response to the issue has been to create the Earthshot Prize, which aims to find solutions through new technologies or policies to the planet’s biggest environmental problems.

The first five winners, who will each collect £1 million ($A1.85 million), will be announced at a ceremony on Sunday.

-with AAP