The head of a union that is one of Labour’s biggest donors has accused the party of “being naive” over its plans to ban North Sea oil and gas production. Labour has pledged to block all new domestic oil and gas developments if it wins power, proposing instead to invest heavily in renewable sources such as wind and also in nuclear power. The proposals, which Keir Starmer is expected to set out formally on a visit to Scotland this month, will involve not only a ban on new North Sea oil and gas licences but also a pledge that any borrowing for investment should be limited to green schemes. But Gary Smith, the general secretary of the GMB union, said on Sunday that the party had “got it wrong” and risked creating “a cliff-edge with oil and gas extraction from the North Sea”. “We are critical friends of the Labour party and I think this is just a lack of intellectual rigour and thinking about where they have got to on oil and gas,” he said on Sophie Ridge On Sunday on Sky News. “They are focusing on what they think is popular rather than doing the proper thinking to understand what is right for the country.” He said the sector had been promised tens of thousands of jobs in renewable energy “time and time again” but that they “simply have not emerged”, adding: “That has been the sorry state of the renewables industry around the country.” The shadow business secretary, Jonathan Reynolds, said earlier on the same programme that the existing oil and gas fields in the North Sea would run until 2050 and the party was not talking about turning those off. “We are against further new licences being granted and that’s because it won’t do anything for bills, it won’t do anything for energy security, it’s not a long-term answer to jobs and clearly it would be a climate disaster,” Reynolds said. “We have got to understand that the opportunity in front of us, the number of jobs created from clean energy, is far in excess of the existing directly employed workforce in North Sea oil and gas.So it’s not some sort of consolation prize, this is the big prize, the big chance to do that, and we will work with Gary in providing this country with a better transition.”