New planning rules have “robust protections” for the countryside, the Government has insisted as it unveiled the final version of its controversial reforms.

Ministers say changes to the planning system, which see more than 1,000 pages of guidance slimmed down to around 50 and focus on a “presumption in favour of sustainable development”, are necessary to boost growth.

But countryside campaigners reacted angrily to draft plans published last year, raising concerns that they could lead to inappropriate development in the countryside - in particular, areas which were not protected by existing designations.

Communities Minister Greg Clark insisted the new planning guidance recognised the “intrinsic value of the countryside”, whether or not it was already designated as green belt, national parks or Sites of Special Scientific Interest (SSSI).

Mr Clark outlined a number of changes to the new national planning policy framework in a bid to answer concerns sparked when the draft version of the reforms were published last July.

They include an explicit return to “brownfield first”, which requires councils to favour previously used land for new development over green field sites and a clearer definition of “sustainable development”.

It will also favour town centres for development.

And it will allow councils with a local plan - intended to set out where development is wanted and needed in an area - that is broadly in line with the new rules to use that for up to 12 months.

But councils with no local plan must use the national planning policy framework from today.

Simon Walker, director-general of the Institute of Directors, said: “Being able to develop new shops, houses and factories is crucial to delivering economic growth, and too often planning regulations have prevented that. The fundamental principle that sustainable development should be supported is a very welcome one.

“To ensure this reform works well, councils must now fulfil their role by putting plans in place that recognise the need to support development.

“Britain needs to get building again, and these reforms allow that to happen - as long as they are followed through.”

But Ruth Davis, from Greenpeace, said: “There is a flawed assumption from George Osborne behind this assault on the planning system - he thinks that we can boost the economy by uprooting decades of protection for the natural habitat and the countryside.

“This is misguided, dangerous and wrong, and appears to be based on little more than some private, cosy chats he has had with big developers.

“Whilst today’s concessions will provide some short-term breathing space for local people seeking to protect the wildlife and places they love, the final test of this policy will be the types of development finally given approval.

“If, in the coming months, we start to see the development of projects that burden communities with more traffic, noise and pollution, suck up scarce local water resources, or destroy precious countryside, not only will it be a political disaster for the Government - they will also be guilty of undermining the future.”

Shaun Spiers, chief executive of the Campaign to Protect Rural England (CPRE), which spearheaded the campaign against the planning reforms, welcomed the recognition of the value of the countryside, whether or not it was protected.

He also said it was good to see the clearer definition of sustainable development, adding: “We are pleased the minister appears to have listened to the strong public views, which mirrored our concerns.”

But he said: “While recognising the scale of the housing crisis, we remain very concerned to ensure that the Planning Framework does not place undue emphasis on short-term economic growth at the expense of other important long-term, public interest objectives of planning, including the protection and enhancement of the environment.”

And he raised concerns about the “transition period” allowing councils to move from their existing local plans to the new rules, which he said at just 12 months would pose a “serious challenge” to many local authorities.

Wouter Schuitemaker, investment director at inward investment programme Business Birmingham – which covers Birmingham, the Black Country and Solihull – said: “Simplifying planning regulations will undoubtedly affect the redevelopment of regional economic hubs such as the Birmingham city region, by removing barriers to growth, boosting investment in infrastructure and unlocking the regeneration of urban brownfield sites. Birmingham already attracts more foreign direct investment than any other regional UK city, and to maintain this influx of finance the Government must provide investors with a warm welcome, not planning delays or red tape.

“Birmingham is already ahead of the game when it comes to presenting investors with a clear local plan that lays out its development objectives. Its Big City Plan is a 20-year vision that aligns Birmingham’s redevelopment with sustainable economic growth – while Local Development Orders set out by the city’s Enterprise Zone are a vital part of its proposition to companies looking to locate in the area.

“By highlighting in his Budget speech that investors are put off by complex planning regulations in the UK, the Chancellor recognised that we need to make it easier for organisations to locate or invest here. Relaxing planning permissions is a clear step forward, but to stimulate more inward investment into regional cities it needs to be complemented with support for local authorities to implement these new regulations as quickly and efficiently as possible.”