Property developers who sit on land should be fined by the government to promote housebuilding in the countryside, according to farming campaigners.

Pressure group Rural plc Kent said stockpiling of real estate is making it more difficult to build affordable homes for those who want to live and work in agricultural and horticultural areas.

It set out the demands in its rural manifesto for the general election, which claims the sector is misunderstood, undervalued and “frequently dismissed as of no consequence”.

As well as considering fines for developers who stockpile building land, it said the government should be “rewarding the development of brownfield and other such sites, the conversion of obsolete farm and other buildings”.

Last year the Local Government Association, which represents councils, suggested there were sites for 500,000 homes in England which had been given planning permission but were yet to be built.

Rural plc Kent’s resources director George Jessel, who is High Sheriff of Kent and owns a farm in Brabourne, near Canterbury, said: “Young farmers and graduates want to have a rural job but the cost of housing in a local village close to work is too high.

“They rely on the bank of mum and dad to support them and the government should be helping people to buy a house.

“Developers are buying huge chunks of land and – because of the economic slowdown – are not building houses where they are needed.

“How do we break that deadlock? We have got to find a way of housing people in areas where they want to work.”

Mr Jessel also called for the removal of stamp duty for first time buyers.

The notion of developers stockpiling land was rejected by Nick Fenton, chairman of Kent Developer’s Group, which represents housebuilders in the county.

He said: “We need to encourage rural development and encourage SMEs to build more but I don’t believe developers are sitting on land.

“I’m sure there are examples of it but some of the figures include sites which are waiting on planning permission and some have planning conditions that need to be met first.

“Also when you give a large scale planning permission for thousands of homes, such as at Ebbsfleet, that won’t happen overnight.

“Usually you will get 40 to 50 units per year. Kings Hill is managing about 150 units a year and I can’t see how anyone else could produce much more.

“We need to encourage the development of rural homes but it is not about accusing developers of sitting on land.”

Rural plc Kent’s manifesto was created partly because “no-one is talking about the rural sector” on the election campaign trail.

The document also calls for a simpler subsidy system for farmers after Brexit and funding to protect rural communities from flooding and climate change.

Mark Lumsdon-Taylor, its human capital director and deputy chief executive of Hadlow Group, is also concerned about the lack of discussion about the UK’s food security after leaving the EU.

Only 60% of food consumed in this country is produced in Britain, while prices of imported goods are rising after the devaluation of the pound following the referendum.

Mr Lumsdon-Taylor said: “We need to talk about the supply chain of food. Supermarkets sell food from farmers but the cost of food is going up.

“People can’t afford fresh produce. We don’t talk about this stuff and we need to.”

Mr Jessel added: “The farming community is taken for granted and it is only when something is going wrong that the industry gets noticed.”

To view the manifesto, contact the group at ruralplc.com