The number of new homes being approved on greenbelt land in England has increased five-fold in five years.

Research carried out on behalf of BBC Radio 4's File on 4 programme found a sharp increase in the number of houses securing full planning approval in the greenbelt.

In 2009-10, planning permission was granted for 2,258 homes. In 2013/2014, the number had risen to 5,607.

By the following year, 2014/2015, it had more than doubled to 11,977.

Housing and planning minister Brandon Lewis said it was for local authorities to decide the future of their greenbelt:

"Greenbelt is something that has been there to give a strategic protection to those green lungs," Mr Lewis told the programme.

"We have outlined what local areas need to do if they want to go through a review of their greenbelt. It is very much a matter of those local authorities.

"They are the best placed people locally, democratically accountable locally, to decide where is the right location for any development."

While some people favour building on greenbelt land, conservationists argue that there are more appropriate places to build houses.

A paper published by the Council to Protect Rural England claims that the nine largest housing developers have 314,000 housing plots in strategic land banks.

It argues that giving local authorities greater powers could greatly increase the number of suitable housing sites being brought forward for development.

The paper, Getting houses built, argues that a focus on profitability within the housebuilding sector is dictating housing supply but not meeting housing need.

This focus has adversely affected the location and build-out rates of new housing, it argues.

Greenfield land is being targeted for its ease and lower risk, while suitable brownfield land nearby remains unused and too few affordable homes are built, says the paper.

The CPRE argues that the system should be reformed to accelerate the supply of homes in the right places, with a number of options to empower local authorities.

These include the suggestion that authorities could be given 'use it or lose it' measures if permissioned land is not developed quickly.

Authorities could learn from European land acquisition models and use reformed Compulsory Purchase Orders (CPOs) to acquire land suitable for housing at existing use value, it says.

Authorities could also levy council tax on housing that is unfinished two years after the granting of planning permission.

CPRE policy advisor Luke Burroughs said: "The need for volume builders to seek high levels of profitability limits the amount of new housing.

"It also delays the delivery of new houses and increases the likelihood of new housing being built in less suitable locations.

"Large scale greenfield sites are forced through the planning system with new housing slowly drip-fed onto the market, while suitable brownfield land remains undeveloped.

"This leaves our countryside under threat and urban areas in need of regeneration."