Opening new oil and gas fields in the North Sea would “send a shock wave around the world”, imperilling international climate targets, undermining the UK’s climate leadership and encouraging developing countries to exploit their own fossil fuel reserves, experts have warned.

The UK government is under stiff pressure from the oil industry, the Conservatives, Nigel Farage’s Reform UK party, some trade unions and parts of the Treasury to give the green light to new oil and gas fields, despite clear evidence that doing so would not cut prices and would have almost no effect on imports.

Two of the biggest fields remaining in the North Sea, which is more than 90% depleted and where the last pockets are increasingly costly and energy-intensive to extract, are within the licensing system. But the Rosebank and Jackdaw fields, if exploited, would displace only 1% and 2% respectively of the UK’s gas imports, research has shown.

Senior figures in international climate diplomacy said drilling new fields would be “dangerous” for global efforts to cut greenhouse gas emissions and phase out fossil fuels.

Nicolas Stern, a professor at the London School of Economics, said: “New drilling and decelerating climate action would be bad for growth and for energy security in the UK, and a damaging signal for the world.”

Lord Stern said: “The UK has been a pioneer in climate action, as the first G7 country to commit to net zero by 2050, through its exemplary climate change legislation, and through its work in international institutions and interactions. Its example matters. Because it has been a pioneer and a leader, the world takes notice of the UK’s actions.”

One senior African negotiator, speaking on condition of anonymity, reacted furiously to the suggestion the UK could open new fields. Africa would “reject any proposal for the UK to expand oil drilling” as such a move would be “fundamentally inconsistent with both the letter and spirit of the Paris agreement” and would “weaken trust with climate-vulnerable nations”, they said.

“At a moment when science is unequivocal about the need for a rapid transition away from fossil fuels, new oil exploration by a historic emitter is as contradictory as it is regressive. It also risks setting a dangerous precedent for other countries to follow,” the negotiator said.

Christiana Figueres, a former executive secretary of the UN framework convention on climate change and a co-founder of the Global Optimism thinktank, said economics as well as the risks of climate breakdown argued against the move.

“It’s entirely understandable that in today’s geopolitical context, countries must seek greater energy security and independence,” she said. “But reaching for solutions of the past – such as expanding oil and gas drilling – risks locking in infrastructure that is increasingly out of step with where the global energy system is heading. True energy independence today lies in scaling clean, domestic energy, not in extending the life of declining industries.”

The UK has been one of the main supporters of a global conference taking place in Colombia later this month on the “transition away from fossil fuels” that countries agreed to make three years ago but have so far failed to implement.

However, the Guardian has learned that Ed Miliband, the UK’s secretary of state for energy security and net zero, will not attend the gathering of about 50 countries. Rachel Kyte, the government’s climate envoy, will go instead.

Campaigners had been calling for the secretary of state to attend as he was widely credited with helping to bring about a last-minute deal at the Cop30 climate summit in Brazil last November.

Experts said that if the UK were to licence new fields before the conference, it could undermine progress on encouraging developing countries to forego fossil fuel-based economies and opt for cleaner energy.

Mohamed Adow, the director of the Power Shift Africa thinktank in Nairobi, said: “The UK approving new oil and gas projects would send a shock wave around the world that short-term interests are being prioritised over long-term responsibility. I dread to think what example that would set to the rest of the world.”

Many developing countries are considering exploiting their own oil and gas resources instead of opting for renewables. If they were to do so, the world would go far beyond the carbon limits needed to stave off the worst ravages of climate breakdown.

Adow said: “Countries across Africa are being asked to leapfrog to clean energy systems, often with limited financial support. We are told, often by European nations, that the future lies in renewables, and increasingly we are proving that it does. When wealthier nations continue to invest in fossil fuels, they undermine this message and diminish their credibility.”

A senior development official in an overseas institution said the question was urgent. “What we are hearing already from developing countries is: why shouldn’t we tap into our own fossil fuel resources if the UK is doing so?” they said. “That is a legitimate point. You have to provide leadership.”

An ally of Miliband said: “No new exploration licences is a landmark global leadership position – a major, developed, oil and gas producing country proving it can walk what it talks on climate and act in line with what the science clearly says to avoid global warming spiralling to a catastrophic 3 or 4C.

“Miliband has taken political heat to protect the position, and the fact that others like [the Green party leader, Zack] Polanski are calling on him to go further is a sign of how far Ed has shifted the Overton window.”

The government has been contacted for comment.