Michael Gove said on Tuesday that a 2030 ban on the sale of new diesel and petrol cars is “immovable,” in a tougher stance than Rishi Sunak.
Downing Street left open the possibility that this target could change, possibly if there were technological improvements in emissions.
But asked on Times Radio, if the 2030 ban was immovable, Communities Secretary Mr Gove said: “Yes.”
Pressed again on this specific point that it would not change, he added: “Yes.”
However, he also stressed that the Government would take into account the costs on people of net zero measures when deciding policies to combat global warming, as parts of Europe were being hit with “toxic heat” record temperatures.
“It’s important that the Government does press ahead with appropriate and thoughtful steps in order to safeguard the environment,” he said.
“But there are some specific areas where the cost that is being imposed on individuals risks creating a backlash.
“We have seen that happen in the Netherlands and we don’t want to get to a situation where the support for improving our environment curdles and turns into resistance.”
Mr Gove’s comments came after Mr Sunak was on Monday not as categoric on the 2030 ban despite Foreign Office minister Andrew Mitchell saying earlier that it was the right decision, amid confusion over what the Government’s exact position was on this issue.
The PM declined in an interview to recommit to the ban on the sale of new fossil fuel cars by the end of the decade in order to reduce emissions as he warned against heaping "hassle" or extra costs on to families.
But asked about the ban, Mr Mitchell told BBC Radio 4’s Today programme, he said: “It is in place...I can’t prophesize for the future.”
Pressed further on the matter, he added: “It is in place and remains in place....and will remain in place.”
Appearing later on GB News, he stressed: “The Government has been very clear that we are phasing them out in 2030 and that is the right policy to pursue.”
Ministers have vowed to protect consumers from “any rising costs” associated with green policies as Conservative MPs called for a “rethink” over the pace of change to reach net zero.
Right-wing Tories are urging the Prime Minister to review the deadlines around environmental measures after voter concerns about the expansion of London’s ultra low emission zone (Ulez) helped the party hang on to Boris Johnson’s old Uxbridge and South Ruislip during last week’s by-election.
The result has given the governing party hope that its chances of pulling off a shock general election victory are not over if it can focus on issues where there is a clear divide with Labour.
Former business secretary Sir Jacob Rees-Mogg and Danny Kruger, the co-leader of the New Conservatives, a group of Tory MPs elected since the Brexit referendum, both called for green deadlines to be reconsidered on Sunday.
Rishi Sunak is said to be considering delaying or ditching climate change-tackling measures that could impose costs on consumers.
One of the options on the table is an exemption for smaller car manufacturers - dubbed an “Aston Martin exemption” - on the 2030 ban on new petrol and diesel cars, according to The Times.
The newspaper said the UK Government is also considering a ban on new low-traffic neighbourhoods (LTNs), with ministers reportedly weighing-up preventing councils from using the national number plate database to stop the zones being enforced.
No 10 said it could not comment on either suggestion although Mr Sunak is likely to be asked about them during a visit to the West Midlands on Monday ahead of the Government unveiling house building reforms.
The Department for Energy Security said the push to net zero would “provide customers with cheaper bills in the long term” but recognised there were concerns about the costs involved with the 2050 target.
A Government spokeswoman said: “We know that the number one concern for families up and down the country today is the immediate cost of living challenge and that’s why halving inflation is one of the Prime Minister’s top priorities.
“We’re working hard to stick to the plan to ease pressure on families, and we will always look to protect consumers from any rising costs.”
Senior Tory Sir Jacob said the lesson from the Uxbridge result, where the Tory majority was slashed from 7,200 to under 500 votes, was that ministers needed to “stop burdening” the public with “extra” green charges and regulations.
He told GB News: “What works is getting rid of unpopular, expensive green policies, and that is a real opportunity for us.”
He proposed “getting rid” of the 2030 ban on new petrol and diesel cars - announced during Mr Johnson’s premiership - arguing it was formulated “a few years ago in different circumstances”.
Devizes MP Mr Kruger told BBC Radio 4’s Westminster Hour: “We shouldn’t abandon green policies but we have got to work in a way that is sensible.
“And I think the whole population, young and old, recognise that we need a transition that is affordable and particularly affordable for working families, people who are struggling to make ends meet.”
It comes as landlords called for more clarity on suggestions from Housing Secretary Michael Gove that a deadline to improve the energy efficiency of private rented homes could be relaxed.
The Government had proposed during a consultation that by April 2025 all new-build tenancies would need a rating of “C” or better, with the same grade applied to all private rented housing by April 2028.
Mr Gove said on Sunday that landlords were being asked to do “too much too quickly”.
Ben Beadle, chief executive of the National Residential Landlords Association (NRLA), said a two-year delay since the original consultation over the measures meant ministers had been warned there was “never any hope of meeting the originally proposed deadlines”.
He said: “The NRLA wants to see properties as energy efficient as possible, but the sector needs certainty about how and when this will happen.
“Ministers need to develop a proper plan that includes a fair financial package to support improvements in the private rented sector.”
Labour overturned a massive 20,000 majority in the by-election in Selby and Ainsty but was left conducting a public inquest into why it had fallen short Uxbridge.
Leader Sir Keir Starmer blamed Mr Khan’s proposals to expand Ulez to all London boroughs for its loss in west London.
Mr Khan, the Labour incumbent in City Hall, plans next month - subject to a legal challenge - to widen the £12.50 daily charge for vehicles which fail to meet emissions standards, taking it beyond the capital’s north and south circular roads.
