Government plans for an overhaul of the planning system – which are claimed to prioritise town centre shops over out-of-town developments – have failed to convince local shop owners that they will be protected from supermarket expansion.

Housing and planning minister John Healey said the revamped system would give local councils “the tools they need to boost business growth and provide new safeguards for town centres and local markets”.

A new impact test replaces the existing need test, under which developments that could harm town centres will be assessed against key factors including climate change, their impact on the high street, consumer choice, consumer spending and jobs.

But ACS chief executive James Lowman said the minister’s rhetoric did not match the detail of the policy. “It will weigh heavily on under-resourced planning departments in local councils, who will have to interpret and implement a policy that is ambitious, contradictory and highly subjective,” he said.

“Ministers have a long way to go to convince us that the new policy will be effective in preventing the highly resourced and determined supermarkets from imposing unwanted new developments on communities.”

He called the removal of the need test “a huge error”. “The replacement impact assessment remains far too vague and subjective for councils to be able to implement effectively,“ he said.

Meanwhile, Tesco has claimed that the new competition test – proposed by the Competition Commission but yet to be endorsed by the government – would stop the creation of 2,500 new jobs a year. However, independent retailers argue that this figure does not take into account job losses and closures of local stores as a result of the multiples’ new developments.

The competition test would ban expansion by retailers with a 60% share of a local market.