Rural campaigners in the East of England have warned David Cameron over his planning policy, saying if he allows 'precious countryside' to be built over it will be gone forever.

The comments from the Eastern region's Campaign to Protect Rural England (CPRE) come after Mr Cameron told MPs the country needs to build on greenfield to meet housing demand.

The prime minister said: 'If we want to build more houses, we will have to build on some greenfield sites.'

Mr Cameron's government has repeatedly targeted the planning system for reform, claiming it is holding back development and the economic growth it can bring.

However Michael Monk, who speaks on behalf of the East of England's CPRE and himself is chairman of the Cambridge branch, disagreed.

He said: 'We do recognise that we need more houses, but that we have to accept the reason more houses aren't being built is not because of planning restrictions but because of the current economic situation.

'I strongly support regeneration in urban areas and the development of brownfield sites, which must come first.

'CPRE research indicates there is sufficient brownfield land to build 1.5m homes in the UK - that has to come first before we use up our dwindling and precious countryside - when it's gone, it's gone. We don't get it back.'

He added: 'I want to underline strongly the point that there is no going back.'

Mr Monk said the CPRE did accept the possibility some greenfield sites would have to be developed, but only as an absolute last resort.

Discussing wider coalition planning policy he said: 'We're concerned about the motivation behind some reforms; that they're intended to weaken, rather than reform the planning system.'