It is understood the Prime Minister is ready to commit to cutting emissions by 78% by 2035 compared with 1990 levels.
The announcement is scheduled to be made ahead of a major US summit on Thursday, where President Joe Biden is expected to set out a new US target for reducing emissions.
It would mark a significant step forward on the current UK commitment to cut emissions by 68% by 2030 – already seen as one of the most ambitious plans among developed nations.
The new target would be in line with the recommendations of the Climate Change Committee, published last year, for the Government’s sixth carbon budget.
In its report the committee said that it would effectively bring forward the UK’s commitment to get to an 80% reduction by 15 years.
In order to be achieved, it said that there would have to be more electric vehicles, an extension of offshore wind power generation, a reduction in meat and dairy consumption and the planting of new woodland.
The pending move comes at a time when the Government is anxious to give a clear lead on climate change in the run-up to the Cop26 talks in Glasgow in November.
The Department for Business, Energy and Industrial Strategy said that ministers would be making an announcement “shortly”.
A spokeswoman said: “We will set our ambition for carbon budget six shortly, taking into account the latest advice from the Climate Change Committee.”
For Labour, shadow business secretary Ed Miliband said the Government had repeatedly failed to match ambitious promises on emissions with effective action on the ground.
“While any strengthening of our targets is the right thing to do, the Government can’t be trusted to match rhetoric with reality,” he said.
“We need a Government that treats the climate emergency as the emergency it is.
“This year, as hosts of Cop26, the UK has a particular responsibility to lead the world and show the way forward for a greener future. This Government isn’t up to the task.”