One of Labour’s biggest donors has pledged to match any public donations to Just Stop Oil in the next 48 hours, as Keir Starmer faced mounting Conservative pressure to return funds from the businessman over his backing for the environmental group. Dale Vince, the founder of the green energy firm Ecotricity, has given at least £1.5m to Labour over the last 10 years, according to the Electoral Commission. Senior Tories including the home secretary, Suella Braverman, and the party chairman, Greg Hands, have accused Starmer of being “in bed” with Just Stop Oil’s backers, claiming that accepting their money is tantamount to supporting the group’s tactics. Braverman questioned whether Starmer was going “soft on crime” as a result of receiving the money from Vince. “He had the cheek to claim Labour is no longer the party of protest this year – the reality is he’s in bed with their donors,” she told the Telegraph. On Twitter, Vince urged people to make a donation to the climate activist group in the next 48 hours. “I will double the amount you give,” he said. “This is what we did after the rightwing mudslinging.” Starmer has previously criticised Just Stop Oil activists, describing their actions as “wrong” and saying they were “arrogant” for thinking “they’re the only people that have got the answer to this”. The shadow international secretary, Nick Thomas-Symonds, defended Labour accepting donations from Vince, insisting it did not affect the party’s views on the campaign group. Thomas-Symonds told BBC Radio 4’s Today programme: “We have been extremely clear on our views on Just Stop Oil. Indeed, Keir Starmer has said of them ‘just go home’ because they are not actually promoting the cause of tackling climate change. What they are doing is entirely counterproductive and the only debate it’s provoking is about our public order laws.” But he said Vince was a “perfectly legitimate person to take money from”. Speaking to the same programme, Vince defended Just Stop Oil’s tactics. “Sometimes laws are unjust and when that happens people have to stand up and do something about it. This climate crisis will be with us for hundreds of years,” he said. Starmer’s pledge to impose a moratorium on new oil and gas projects puts Labour policy in line with a demand of Just Stop Oil but Vince denied that his donations had influenced the policy. “That’s not connected to donating to them. I’ve been doing that for years, since Ed Miliband was leader,” he said. “Keir Starmer has already said he’s going to do this, at Davos, so this isn’t a new story. It’s a mudslinging exercise, trying to make a whole lot of fuss about something, trying to create some smoke and pretend there’s a fire.” He added: “I think it is a desperate stretch for the rightwing press and Tory MPs actually to be saying there’s a link here, that this money should be given back. The money is not dodgy.” In a letter to the Labour party chair, Anneliese Dodds, on Sunday, Hands said he was concerned about the influence of Vince’s donations, highlighting how Labour had voted against legislation to crack down on disruptive protests. “I am calling on you to return these donations,” he wrote. Just Stop Oil protesters slow-marched in Parliament Square on Wednesday and arrests were made after some refused police orders to leave the road.