“It was unanimously agreed that this would not be the right occasion for the King to visit,” she said, adding: “I’m not aware that that advice has changed.”
John Kerry, the US climate envoy has urged Downing Street to rethink its bar on the King attending Cop27, pointing to his long history of environmental campaigning.
The call came after Mr Sunak – amid widespread criticism – announced he would skip the event because of what No 10 called “pressing domestic commitments”.
The prime minister must prepare for the de-facto budget now delayed until 17 November, when huge spending cuts and tax hikes will be unveiled, Downing Street indicated.
Earlier, the environment secretary Therese Coffey provoked astonishment by dismissing Cop27 as “just a gathering of people in Egypt”.
She also described the Cop26 that the UK hosted in Glasgow as “a success” – despite is failure to set the world on a path to keep temperature rises below 1.5C.
Ms Coffey also claimed, on the issue of whether the King should go: “I think it’s up to him. I know that he takes an interest in this particular issue, but it’s up to him.”
But Downing Street confirmed the previous prime minister had stepped in to keep the King away from Egypt, as reported earlier this month.
“As is standard practice, government advice was sought and provided under a previous PM and it was unanimously agreed that it would not be the right occasion for the King to visit in person,” she said.
“I’m not aware that that advice has changed, but obviously any confirmation of the King’s travel would be for the palace.”
Asked if Downing Street would reopen the conversation with the palace – now Mr Sunak is not attending – the spokeswoman repeated that she was unaware of the advice changing.
Nadine Dorries became the first Conservative MP to criticise Mr Sunak’s decision, tweeting: “The prime minister is WRONG not to go to COP. Global warming is the biggest crisis facing our planet and net zero creates many 1000s of jobs which is good for the economy.”
But, speaking on a visit to a London hospital, Mr Sunak denied a failure of leadership, claiming: “The leadership that we have shown on the climate is unmatched almost along the world.”
He added: “It’s important to me, as prime minister, we leave behind an environment that is better for our children and grandchildren. I’m very passionate about that. I’m very personally committed to it.
“I just think, at the moment, it’s right that I’m also focusing on the depressing domestic challenges we have with the economy. I think that’s what people watching would reasonably expect me to be doing as well.”