Rishi Sunak has accused Lord Zac Goldsmith of resigning with a scathing attack on the Government’s environmental “apathy” after refusing to apologise for a campaign to undermine an investigation into Boris Johnson.

The ally of the former prime minister dramatically quit his Foreign Office role on Friday, accusing Mr Sunak of being “simply uninterested” in tackling the climate crisis.

However, the Prime Minister hit back by making clear that Lord Goldsmith had been asked to apologise over his comments about the Privileges Committee inquiry that found Mr Johnson lied to MPs with his partygate denials.

Mr Sunak noted the Tory peer “decided to take a different course” but said the apology was necessary because his remarks were “incompatible” with his position as a minister.

Lord Goldsmith, who was handed his peerage by Mr Johnson,  announced his resignation a day after being named by the Privileges Committee as one of eight parliamentarians who had launched “attacks” on its work.

In a second statement following his resignation “for clarity,” the Tory peer countered Mr Sunak by claiming he was “happy to apologise” for sharing his views on the inquiry and accused No 10 of “misleading briefing”.

Writing to Mr Sunak, the Tory peer who had the environment in his brief as a minister in the Foreign Office, said he had been “able to get so much done previously” but has “struggled even to hold the line in recent months”.

“The problem is not that the Government is hostile to the environment, it is that you, our Prime Minister, are simply uninterested,” Lord Goldsmith wrote.

“That signal, or lack of it, has trickled down through Whitehall and caused a kind of paralysis.

“This Government’s apathy in the face of the greatest challenge we have faced makes continuing in my current role untenable.”

Mr Sunak’s attempt to portray his Government as working to fix the problems in the NHS with a workforce plan on Friday was rocked by the resignation.

“Thank you for your letter. I accept your resignation,” Mr Sunak responded to Lord Goldsmith.

“You were asked to apologise for your comments about the Privileges Committee as we felt they were incompatible with your position as a minister of the crown. You have decided to take a different course.”

Hours later, Lord Goldsmith wrote: “In response to some misleading briefing from Number 10, I’d like to make clear I am happy to apologise for publicly sharing my views on the Privileges Committee.

“I firmly believe our Parliamentary democracy can only be strengthened by robust exchange and scrutiny and Parliamentarians should of course be free to be critical of its reports & proceedings.

“But as a Minister I shouldn’t have commented publicly.

“Number 10 asked me to acknowledge that and made clear there was no question of my being sacked if I did so. I was – and am – happy to do so.”

Mr Sunak was forced to defend his “proud” track record at a Downing Street press conference on the NHS, saying the UK will continue to play a “leadership role globally” on the environment.

In a report on Thursday accusing the group of MPs and peers of a campaign to interfere with its work, the Privileges Committee cited a retweet posted by Lord Goldsmith in June which suggested it was a witch hunt and a kangaroo court.

“Exactly this,” Lord Goldsmith had added.

“There was only ever going to be one outcome and the evidence was totally irrelevant to it.”

Downing Street sources told the PA news agency Lord Goldsmith was asked to apologise on Thursday afternoon after featuring in the damning report.

Until he quit, Downing Street had been saying Mr Sunak had full confidence in him as a minister despite the findings.

The committee said the Commons should consider whether the actions of MPs involved, including staunch Johnson loyalists Nadine Dorries and Sir Jacob Rees-Mogg, amounted to contempt of Parliament, as well as what further action to take.

Labour’s shadow environment secretary Jim McMahon said: “Rishi Sunak’s weakness is laid bare as 24 hours after he refused to condemn Zac Goldsmith, Goldsmith scathingly condemns him.

“This ‘simply uninterested’ Prime Minister can’t lead his own team, never mind lead the country.

“The Conservatives are in disarray – with mortgages soaring, NHS waiting lists rocketing, and in their own words: ‘Apathy in the face of the greatest challenge we face’.”

The Liberal Democrats said the Prime Minister should have “had the guts” to sack Lord Goldsmith the day before his ministerial resignation following his “brutal” censure.

Rishi Sunak
Prime Minister Rishi Sunak during a press conference in Downing Street in London, as the NHS (Frank Augstein/PA)

Sarah Olney, the party’s Treasury spokeswoman, said: “This Conservative chaos is never-ending.

“Every day brings more more resignations and scandal in this depressing Westminster soap opera.

“Rishi Sunak should have had the guts to sack Zac Goldsmith yesterday when he was brutally criticised by the partygate watchdog.

“Sunak is clearly too weak to control his own party.”

Mr Johnson and his allies have been creating a steady stream of headaches for Mr Sunak, with the former prime minister resigning as an MP in anticipation of the Privileges Committee report.

Nigel Adams followed him out of the Commons, setting up two challenging by-elections for the Conservatives at a time when they are trailing far behind in the polls.

Ms Dorries, perhaps Mr Johnson’s staunchest ally, also announced her intention to quit with “immediate effect” but is yet to do so formally as she seeks answers over the peerage she never received.