Three political leaders have jointly written to the Government requesting a limit on the number of homes built on green belt land in their area.

The leaders of Three Rivers District Council and St Albans District Council, along with St Albans MP Daisy Cooper, wrote to Housing Minister Robert Jenrick with concerns about housing targets.

Councils across the country have been told to find space to build thousands of homes over the next 15 years or so to help meet aspirational targets by the Government to build 300,000 homes a year.

In Hertfordshire, this means vast green and currently protected open spaces are at risk - the Countryside Charity says local authorities in Hertfordshire are allocating 54,537 new homes on green belt land, which is on top of around 17,000 that have been approved or are being built.

On August 31, St Albans MP Mrs Cooper sent a letter to Mr Jenrick with three requests.

The letter was co-signed by Cllrs Sarah Nelmes and Chris White; the respective leaders in Three Rivers and St Albans.

The requests were the Government "urgently update" a national planning policy to "reflect the Government's position that housing calculations are 'only a starting point' and 'not a target' by removing the ability of the Planning Inspectorate to use the standard calculation in assessing local plans and in deciding planning appeals".

The second is to "introduce a limit on how many homes should be built on green belt" and that "any excess be allocated to areas without green belt", and failing that, allow Three Rivers District Council to use its most up-to-date census data to calculate housing targets rather than 2014 data from the Office for National Statistics.

The third request is for the Government to set out what other measures it intends to take to enable councils to protect Hertfordshire's green belt.

According to council papers published by Dacorum Borough Council in July, on 21 June this year during a parliamentary debate on planning decisions, the housing minister restated the Government's "commitment" to protecting the green belt, explicitly stating local authorities should not develop on the green belt, except for in exceptional circumstances.

But the Countryside Charity claimed there was a "growing disconnect" between recent Government statements and the application of planning policy at a local level.

A spokesperson for the Ministry of Housing, Local Government, and Communities told the Observer in late August that protecting the green belt is a "priority" and that "decisions to release green belt land are made by local councils, not central government".

But the department failed to respond to a question about whether councils could face sanctions for demonstrating in its Local Plan that it could not meet targets without building on the green belt.

Related: Government claims protecting green belt a 'priority'

Watford Observer: Campaigners from Carpenders Park at a protest in August Campaigners from Carpenders Park at a protest in August

In their letter to Mr Jenrick, Mrs Cooper, Cllr White, and Cllr Nelmes say the green belt is a "vital resource" that provides "habitats for wildlife, agricultural use, local food, relaxation and fresh air", as well as "preventing urban sprawl".

They added: "We know that the country needs to build more homes, but the government’s approach isn’t working."

They also mentioned a local case study in which a planning inspector overturned a decision made by a council to refuse 100 homes on green belt land in Colney Heath despite opposition from residents - the Lib Dem politicians said a central Government body favouring "crude targets over local concern is an egregious attack on local democracy".

They continued: "If we want to increase housing we need to start with the one million homes that have planning permission approved but have yet to be built."