Fears have been raised that new measures blocking housing developments in certain parts of Norfolk could lead to a free for all in those places not covered.

Earlier this month, government advisor Natural England told all Norfolk councils they must not grant planning permission in certain areas for schemes involving 'overnight accommodation' until it could be proved they would not lead to phosphates and other nutrients flowing into the River Wensum and the Broads.

The changes to the planning system are intended to keep waterways clean. However, concerns have been raised they could lead to developers bringing back rejected plans in areas not covered by restrictions.

Meanwhile, in another twist South Norfolk MP Richard Bacon has today warned the changes have thrown the planning system into "something approaching chaos".

Natural England and the Department for Environment, Food and Rural Affairs (Defra) say councils need to make assessments against which developers can prove their schemes are nutrient neutral by providing mitigation if necessary.

This means schemes for new houses, student homes, care homes and campsites, cannot go-ahead until measures are put in place in the areas covered to prevent pollution.

But Mark Ashwell, planning policy manager at North Norfolk District Council, warned councillors on the planning policy and built heritage working party, that it could lead to developers pushing plans in the areas not covered by 'nutrient neutrality' rules.

While a large part of Norfolk is covered by the new restrictions, large areas along the coast, including a stretch between Burnham Market and North Walsham in north Norfolk, avoid the measures.

Mr Ashwell said: “Authorities which are split in this way, where part of their district is covered and the other bit isn’t, will find it very difficult to resist development proposals in the bit that’s not covered."

Current planning rules mean favour should be given to development unless the "harmful impacts are really significant".

Mr Ashwell said he expects “shrewd developers”, who have been turned down in the past or who wish to develop outside of local plan areas, will resubmit their plans, making a case that the council will struggle to meet housing supply needs without it.

Local authorities are required to demonstrate that they have five years of land available for housing and nutrient neutrality may mean councils struggle to meet the goal.

Mr Ashwell added: “We are looking at what mechanisms we can employ to prevent that unfortunate redistribution of growth into areas where we wouldn’t normally want it.”

However, Mr Ashwell said north Norfolk may fair better than other authorities because the areas outside the new rules are in the area of outstanding natural beauty - spaces already designated for conservation.

What are Norfolk's MPs saying?

Norfolk MPs have been split on the issue of the planning changes.

The harshest criticism came from South Norfolk MP Richard Bacon, who said: "Natural England Strikes again.

"Merely by issuing extra information on water quality and nutrient neutrality, Natural England has succeeded in placing local planning authorities in a legal limbo where planners' own legal advisers are now telling them to take what is in my view an absurdly over-cautious approach to issuing planning permissions."

Mr Bacon said the effect on small housebuilders has been catastrophic, with many suddenly discovering they have fallen at a hurdle they did not know was there.

He called on the government to sort the mess out as quickly as possible.

On the other side of the argument is Norwich South MP, Clive Lewis, who praised the effort to clean up the waterways.

Mr Lewis tweeted last week: "If developers can’t or won’t guarantee that then the development shouldn’t happen."

North Norfolk MP Duncan Baker said he has concerned the rules had been misinterpreted by councils and was seeking advice from the government's planning minister for a sensible solution.

North Norfolk's local plan

North Norfolk's planning policy boss also raised concerns about what the changes would mean for the district's local plan.

The local plan is a document setting out where North Norfolk District Council (NNDC) would like to see around 9,6000 homes built over the next 15 years.

NNDC had been gearing up to submit the plan, having run a public consultation which ended in February.

Areas like Fakenham and North Walsham, where almost 3,000 homes are planned across the two towns, are covered by the new rules.

Mr Ashwell warned that if the local plan did not address nutrient neutrality and mitigation measures it could be unlawful, unsound and would likely be rejected by government inspectors.

The planning manager said there were probably dozens of forms of mitigation but at the moment the authority has limited knowledge of them.