Keir Starmer’s promise to block new North Sea oil and gas exploration has received the backing of an eclectic range of high-profile groups, including environmental campaigners, trade unions and even the Women’s Institute. The Labour leader is set to unveil his net zero energy policies during a speech in Scotland this month, including a radical pledge to ban all North Sea oil and gas licences. The promise is a key plank of Labour’s environmental platform, but has sparked anger among business and political leaders in the north-east of Scotland, where the industry is concentrated. The Labour leader is being urged to stick to the plan in a letter signed by 139 organisations, including the Campaign to Protect Rural England, the Royal Society for the Protection of Birds and the National Federation of Women’s Institutes. The groups write: “We urge you to stand firm on Labour’s policy of no new oil and gas developments and its significant investment in well-planned, nature-positive renewables and energy efficiency, and to confirm more details on how Labour will support workers to transition from fossil fuels to good quality, secure green jobs during your speech in June.” Shadow ministers confirmed last month that the party intended to ban new domestic oil and gas developments as part of its strategy to achieve zero-carbon power by 2030. Starmer will formally announce the pledge as part of a speech later this month setting out his green agenda in more detail. But the plans have attracted criticism from the Conservatives, the leader of the GMB union, as well as Aberdeen-based business leaders. Grant Shapps said the plan was an “ideological vendetta against British energy independence”, saying it would risk jobs and boost Russia’s global power. Rishi Sunak, the prime minister, has said it would be “economically illiterate” not to invest in new UK oil and gas. The energy secretary is due to make a decision in the next few weeks over whether to approve drilling at the giant Rosebank oil field off Shetland. Sunak’s comments have been interpreted as a sign the government is prepared to give it the green light, although investors have said Labour’s green policies could make it less attractive to investors. The GMB union general secretary, Gary Smith, said Labour’s policies “are going to create a cliff edge with oil and gas extraction from the North Sea”. Speaking on Sky News on Sunday morning after the shadow business secretary, Jonathan Reynolds, defended the party’s plans to ban oil and gas production, Smith described Labour as “naive”. In an article for the Times, Ryan Crighton, the policy director of Aberdeen and Grampian Chamber of Commerce, wrote: “If the alternative is importing, at a greater carbon cost, then surely the UK should always favour domestic production, where we can control the regulatory environment.” The high-profile opposition to Labour’s plans has caused concern among environmental groups, with Labour having recently backtracked on a range of other policies, including a pledge to abolish university tuition fees. Starmer is also under pressure from some of his frontbench to change the remit of the party’s £28bn climate fund to allow it to invest in infrastructure projects that are not explicitly green in nature. Tessa Khan, the founder of Uplift, a group that campaigns for the UK to move away from fossil fuels, and which signed the letter, said: “We were disturbed by the way in which Labour’s position to oppose development of new oil and gas field has come under attack in the last week. “We wanted to make it clear that it is a core position of the climate sector and more broadly among different sectors in the UK. It’s a mainstream position and backed up by climate science.”