Public bodies such as government, schools and hospitals could bring about significant improvements in UK farming by ensuring that they buy their food from sustainable and ethical sources, according to Friends of the Earth.
The environmental group insisted that the policy would help British farming as well as being an important step in tackling climate change.
Their comments followed a speech by the Tories’ Shadow Environment Secretary Nick Herbert, in which he said it is time for a government which "cares about British farming".
“The government, along with school authorities and the NHS, should be supporting UK farmers by buying British food in all of their departments, schools and hospitals,” said Vicki Hird, Senior Food Campaigner at Friends of the Earth.
But she was quick to add that “it must also be food that has been produced without trashing rainforests”.
The Conservative MP Peter Ainsworth last week proposed a Sustainable Livestock Bill with cross-party support. It includes plans to reduce the environmental impact of the UK's meat and dairy consumption.
While there is no chance of the Bill becoming law before the general election, Friends of the Earth plan to press for it to become law in the next Parliament, regardless of which party is in power.
The group say that they want to expose the “hidden link between the food on our plate” and climate change and deforestation.
They add that the meat and dairy industry is responsible for 18 per cent of global greenhouse gas emissions and that if current trends continue, farming for animal feed and cattle ranching alone will destroy 40 per cent of the Amazon rainforest by 2040.
"Large-scale industrial farming in this country is now a major cause of greenhouse gas emissions and the loss of wildlife,” insisted Hird, “Rainforests in South America are being cleared to grow animal feed destined for UK factory farms”.
Friends of the Earth report that 259 MPs and 30,000 farmers and consumers around the country have so far backed their call for what they describe as “planet-friendly farming”.
Hird said that the next government could “demonstrate real commitment to tackling climate change by ending funding for factory farming and supporting British farmers to graze animals and feed them home-grown diets."