The government faces a potentially serious rebellion over its plans to centralise and accelerate the housebuilding process in England after Theresa May led a string of senior Tory MPs in expressing opposition to the proposals in parliament. May, speaking in a Commons backbench debate organised by another Conservative MP, Bob Seely, said that while she and others fully supported the need for more homes to be built, ministers must “think again on this”. The former prime minister, who has in recent weeks also been a vocal critic of the government’s plans to break international law by unilaterally rewriting parts of the Brexit withdrawal agreement, said the plans would remove local decision-making, build over rural areas, and not deliver the affordable homes needed. “We do need to build more homes, but we won’t do that by forcing local authorities to grant more planning permissions to developers so that they can build more homes to bring the price down – because developers simply won’t do it,” she said. “The government does need to think again on this and it needs to understand the impact that the proposals it has put forward are going to have.” The planning changes, set out in a white paper in August, would remove councils from many routine decisions and instead use an algorithm to set new housing targets for local areas. Analysis of the algorithm has alarmed many Tory MPs and councillors after it suggested that many of the homes needed for an annual target of 333,000 would be built in Conservative heartlands such as Kent and Surrey. The backbench motion by Seely, which has no force on the government, requests that the new system is not introduced without a debate and a vote in the Commons. Seely, the Isle of Wight MP, said the algorithm risked ensuring that with new homes, “the biggest housing increases will be to rural shires and suburbs, and the biggest falls are in the urban north and Midlands”. Virtually every Tory MP who spoke criticised the plans, with former May-era cabinet minister Jeremy Hunt saying they risked “eroding local democracy, reducing affordable housing and encroaching on our beautiful countryside”. He added: “The government must think again.” Damian Green, the Ashford MP and former de facto deputy to May, said he and other Kent MPs were deeply worried. “Algorithms are a tool for mathematicians, not politicians,” he said. “We are in danger of turning the garden of England into a patio.” Other Tory former ministers who joined in the criticism included Chris Grayling, who said the plans would merely “suck growth” into the south-east of England, Damian Hinds and Caroline Nokes. Nokes, the former immigration minister, said local councils were better able to decide where new housing should be built. “Let local councillors who have a track record of delivery carry on delivering,” she urged. Boris Johnson’s spokesman said no action would mean people being less able to buy a home. He said: “That’s why we must reform the planning system to cut red tape and make the system faster, while ensuring that councils and local people can decide where developments should and shouldn’t go.” Asked about the Tory MPs’ worries that the algorithm would mean building money being pulled into the south of England rather than the north or Midlands, he said: “The changes that we have put forward are part of a consultation, so naturally we will listen to the feedback to ensure we do this in the best way.”