Building on green belt land will not solve the UK’s “affordability crisis” and only “entrench the issue” according to campaigners who have warned about the alarming rate protected areas are being eroded.

According to the Campaign to Protect Rural England (CPRE) 78% of the 460,000 homes planned on land released from the green belt will not meet the government’s definition of affordable. The group’s annual State of the Green Belt report says last year 72% of homes built on greenfield land within the green belt were unaffordable by the government’s definition.

CPRE claim government housebuilding targets will mean more land being stripped out of the green belt for development despite the fact that there is enough brownfield land within England to accommodate more than one million homes. Local authorities with green belt land are said to have enough brownfield sites for 720,000 homes.

Tom Fyans, director of Campaigns and Policy at the CPRE, said: “We are being sold a lie by many developers. As they sell off and gobble up the Green Belt to build low density, unaffordable housing, young families go on struggling to afford a place to live. The affordable housing crisis must be addressed with increasing urgency, while acknowledging that far from providing the solution, building on the Green Belt only serves to entrench the issue.”

CPRE are calling on the government to:

• Retain its commitment to protect the Green Belt by establishing long-term boundaries
• Halt speculative development in the Green Belt
• Develop clear guidance for local authorities on housing requirements to protect designated land
• Support the creation of new Green Belts where local authorities have established a clear need for them

“The government is failing in its commitment to protect the Green Belt – it is being eroded at an alarming rate,” Fyans added. “But it is essential, if the Green Belt is to fulfil its main purposes and provide 30 million of us with access to the benefits of the countryside, that the redevelopment of brownfield land is prioritised, and Green Belt protection strengthened.”

A spokesman from the Housing, Communities and Local Government department said: "We are clear that building the homes our country needs does not mean tearing up our countryside. Last year the number of new homes built was the highest in a decade, and only 0.02% of the green belt was developed for residential use. We are adding more certainty to the planning system and our new planning rulebook strengthens national protections for the green belt, and says that councils may only alter boundaries in exceptional circumstances once they have looked at all other options."