The previous government in London committed in 2021 to curb such emissions by 78 percent over the same period compared to 1990.

Starmer unveiled the new target as he attended the beginning of the COP29 climate conference in Baku, Azerbaijan, where he is one of the only G20 leaders to show up.

The summit's start has been overshadowed by the re-election in the US of longtime climate change sceptic Donald Trump, as well as new warnings that 2024 is on track to break temperature records.

UK Labour party leader Starmer, who took power in July, told a press conference that Britain was "building on our reputation as a climate leader".

"I've had a series of meetings here at COP this week because this government recognises that the world stands at a critical juncture in the climate crisis," he said.

"There is no national security, there is no economic security, there is no global security without climate security."

The British leader insisted his government was not going to "start telling people how to live their lives" in order to meet the new emissions reduction target.

"We're not going to start dictating to people what they do," he added.

Starmer touted efforts already put in place by ministers to meet what he called an "ambitious" but "realisable target", including ending an effective ban on new onshore wind projects.

His Labour government has also said it will not issue any new oil and gas exploration licenses in the North Sea, and closed the UK's last coal power plant in September.

Starmer said that meant Britain was the "first G7 economy to phase out coal power", and that it was now prioritising renewable energy projects.

"Make no mistake, the race is on for the clean energy jobs of the future, the economy of tomorrow," he said.

"And I don't want to be in the middle of the pack. I want to get ahead of the game."

Environmental groups cautiously welcomed the new 2035 target.

Friends of the Earth's head of campaigns, Rosie Downes, called it "a step in the right direction but must be seen as a floor to the level of ambition not a ceiling".

"Deeper, faster cuts are needed to help avert the climate collision course we are on," she added.

"Furthermore, if these targets are to be credible, they must be backed by a clear plan to ensure they are met. The UK's existing 2030 commitment is currently way off course."