Former prime minister theresa may has become the most high-profile critic of the uk governments new planning reforms as she begged downing street to reconsider the ill-conceived policy.

Boris johnson is pushing ahead with a new us-style plan for councils to designate all land either for preservation or development, with a national target of more than 300,000 new homes a year to be divided among local authorities.

But the plan has caused uproar among many tory mps who believe it will lead to swaths of development in leafy southern shires while not delivering enough new homes in northern england.

Most controversially, the new homes are to be allocated to local authorities according to a computer algorithm based on factors including demographic growth and previous provision of housing supply.

Mrs may, who was prime minister until 2019, said the mechanistic approach did not guarantee a single extra home being built. instead of levelling up it forces more investment into london and the south, she said.

The former prime minister said she agreed with the need for more homes to be built in england. but we wont do that by removing local democracy, cutting the number of affordable homes that will be built and building over rural areas, but that is exactly what these reforms will lead to, she said.

Mrs may added that even if authorities gave more planning permissions to developers it would not guarantee that prices would come down, given the tendency for housebuilders to sit on authorisations.

Jeremy hunt, former foreign secretary, also spoke out against the plans, warning that simply increasing housing targets did not necessarily help people get on to the housing ladder. the plans risked eroding local democracy, cutting affordable housing and encroaching on our beautiful countryside, he warned.

Chris grayling, former transport secretary, said the plans would be counter-productive and would continue to suck economic growth, the brightest and best people in our society, [and] opportunity into the south-east of england.

The ministry of housing, communities and local government said the housing algorithm had been set up to deliver the new homes the country needs.

But mrs may, in a reference to another controversial algorithm used to decide a-level results this summer, said:i might have thought the government would have abandoned algorithms by now.

The comments came in a backbench debate proposed by bob seely, tory mp for the isle of wight, who said it was time to stop the drift of jobs and opportunities to southern shires and suburbs.

Damian green, another former cabinet minister, said mps were increasingly worried about the proposals. we are in danger of turning the garden of england into a patio.