Andy Burnham has declared climate change as a “national security issue” as he told the UN Cop31 summit that “Britain is back”.

Attending the annual conference for the first time in his capacity as prime minister, Mr Burnham insisted that “Britain will answer the call” when it comes to action on climate change.

Amid accusations that his government is deprioritising the green agenda, he confirmed the UK is committed to meeting its 2050 net zero target and working with other countries to reach theirs.

During his speech to in Turkey, he warned that the “climate crisis is upon all of us now” after a “not normal” summer of extreme heat, wildfires and drought.

“The climate crisis is not a distant threat; it is upon us all now, devastating lives and livelihoods everywhere,” he said.

“Meanwhile, two wars across two continents have sent fuel prices and gas bills soaring for families and businesses across the world. The common thread running through all of this: our dependence on fossil fuels.

“The message I carry here at my Cop as UK Prime Minister is this, we’re committed to meeting our 2050 net zero target, and committed to working with all of our partners to reach theirs.”

But climate campaign group Greenpeace said that the imminent decision on the Rosebank oil field and speculation about the watering down of electric vehicle mandares threaten to “drown out” the prime minister.

“Andy Burnham’s COP speech hit the right notes, but the noises off stage about a massive new oil field and laxer rules on electric cars almost drowned him out,” Greenpeace UK head of politics Ami McCarthy said.

Appointing the world’s first climate security envoy is a welcome move, but approving Rosebank would only increase the climate threat level to communities in Britain and around the world. Supporting an ambitious global electrification goal is the right thing to do, but the gesture feels hollow without signing up to the pledge and with the cabinet discussing watering down our own EV targets back home.

They added: “There are so many elephants in the room you’d think it’s a zoo. Burnham needs to start bridging the widening chasm between words and deeds on climate action.

“The choices he makes over the coming weeks and months will decide if his speech today was more than hot air.”

The gathering takes place against a backdrop of rising global oil and gas prices triggered by conflict in Iran, which has forced countries to re-evaluate energy strategies.

Questions over Mr Burnham’s environmental commitment have grown amid reports ministers are considering reducing electric vehicle sales targets by roughly a quarter.

Government approval of the Jackdaw gas field in the North Sea has also drawn sharp criticism from campaigners, who are urging the administration to block the even larger Rosebank oil project.

Ahead of the trip, Mr Burnham sought to underline his green agenda by welcoming a £12 billion investment in offshore wind farms off the Norfolk coast, which includes £1 billion from the state-backed National Wealth Fund.

Mr Burnham is expected to be the only G7 leader to address the summit in the Mediterranean resort city of Antalya, with US President Donald Trump declining to send a delegation for the second year running.

China’s Xi Jinping and India’s Narendra Modi, whose countries rank among the world's largest emitters of greenhouse gases from fossil fuels, are also absent from the summit.

He was the first speaker at the conference on Thursday, addressing a half-empty plenary hall at the start of the session with Foreign Secretary Ed Miliband and London Mayor Lord Sadiq Khan in the audience.

He also appointed a climate security envoy to prioritise the identification of climate risks as a matter of national security.

Dame Madeleine Alessandri, chairwoman of the Joint Intelligence Committee, will also be tasked with strengthening international partnerships over climate issues.

Dame Madeleine stated she would "work with partners across government and internationally to strengthen our understanding of climate threats, build resilience, and ensure we are better prepared for the challenges ahead."

Mr Burnham is also expected to meet Brazilian President Luiz Inacio Lula da Silva on the sidelines of the event to discuss efforts to protect the Amazon rainforest.