Plans to bring forward the end of new petrol and diesel car sales to 2035 will be announced by Boris Johnson today.
The Prime Minister will be joined by Sir David Attenborough at the launch of the COP26 UN Climate Summit.
In a speech at the launch, the PM will reveal plans to end the sale of petrol, diesel - and for the first time hybrid vehicles - five years earlier than planned.
And ministers say it could happen sooner if a quicker transition is feasible.
It comes after the Tory government had been slammed for acting too slowly over its polluting vehicles ban.
Government advisers the Committee on Climate Change called for the ban by as early as 2030.
The Committee had warned domestic action to slash carbon dioxide and other greenhouse gases was lagging far behind what is needed - even before the overall net-zero target of 2050 was set.
The Prime Minister is also expected to use the speech to call for international action to achieve global net zero emissions.
Mr Johnson will say: "Hosting COP26 is an important opportunity for the UK and nations across the globe to step up in the fight against climate change.
"As we set out our plans to hit our ambitious 2050 net zero target across this year, so we shall urge others to join us in pledging net zero emissions.
“There can be no greater responsibility than protecting our planet, and no mission that a Global Britain is prouder to serve.
"2020 must be the year we turn the tide on global warming– it will be the year when we choose a cleaner, greener future for all.”
The PM will also be joined by Italian PM Giuseppe Conte at the event, to be held in central London.
Plans for the crunch summit itself will take place in Glasgow in November been mired in controversy in recent days.
Claire Perry O'Neill, a former Conservative MP, was removed from her post as president of the event, which will take place in Glasgow.
Nick Mabey, chief executive of climate change think tank E3G, said the UK's presidency had got off to a bumpy start with the decision to dismiss her.
Her replacement has a "daunting task" and would need to be a political heavy hitter, with an immense diplomatic effort needed from the UK to steer the negotiations, he said.
"A successful presidency could bring about transformational changes in the global economy that would accelerate the transition to net zero and improve our resilience to climate risks.
"Importantly, it would reinforce trust that the Paris Agreement is working - an essential outcome in the face of Trump, Putin and Bolsonaro, whose disdain for multilateralism threatens the possibility of a climate safe world," he said.
Edmund King, AA president, said the new target on car sales was incredibly challenging.
He added: "We must question whether we will have a sufficient supply of a full cross-section of zero emissions vehicles in less than fifteen years.
"We will also need a package of grants coupled with a comprehensive charging infrastructure at homes and in towns, cities, motorways and rural locations.
"At the very least the Government should take up the AA demand to cut VAT on new EVs to boost sales and make vehicles more affordable to those on lower incomes."
He also raised concerns that hybrids would be excluded from sale under the plans.
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