“I stand by the manifesto on that,” the new prime minister told MPs in the Commons – referring to the 2019 moratorium on drilling for shale gas.
However, Mr Sunak hinted he would also bring back the effective ban on onshore wind farms, which is predecessor also planned to remove to boost the UK’s energy supplies.
He also failed to commit to raising benefits in line with inflation – rather than much-lower wages – in the ‘budget’ now delayed to 17 November.
The moves came as the prime minister refused to deny that his officials have raised fears about the controversial return of scandal-hit Suella Braverman to the cabinet.
Asked whether he will cooperate fully with the contempt inquiry into whether Boris Johnson lied to parliament over No 10 parties, Mr Sunak replied: “Of course.”
It was the lifting of the fracking ban that brought down the curtain on Ms Truss’s disastrous premiership – after a Tory revolt amid farcical scenes in the Commons last week.
The former prime minister angered her own MPs, and independent experts, by arguing the soaring price of gas had created an opportunity for the UK to exploit its underground reserves.
The claim was dismissed by the head of a government watchdog, who warned it would not ease the UK’s energy crisis and could cause “serious” environmental damage.
The 2019 election manifesto promised the moratorium would continue unless scientific evidence had found the risk of earthquakes has been reduced – but a review found it had not.
In fierce exchanges, Mr Sunak attacked Keir Starmer on all the fronts that will be popular with the right flank of his party – underlining the vulnerability behind the return of Ms Braverman.
He accused the Labour leader of being “soft on crime and in favour of unlimited immigration”, claimed he “rarely leaves north London” and that he “tried to overturn” the Brexit vote.
But Sir Keir focused on the economy, ahead of big spending cuts on 17 November, arguing his opponent is “not on the side of working people”.
“That’s why the only time he ran in a competitive election he got trounced by the former prime minister, who herself got beaten by a lettuce,” he taunted Mr Sunak.
“So why doesn’t he put it to the test, let working people have their say and call a general election?”
The prime minister insisted: “Our mandate is based on the manifesto that we were elected on – to remind him, an election we won and they lost.”
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