EU member states Tuesday agreed to unpick more eco-friendly requirements under the bloc's common agricultural policy (CAP) in a new bid to pacify months-long protests by farmers -- who rolled hundreds of tractors into Brussels to vent their grievances.

A special committee endorsed the review to be debated by agriculture ministers meeting in Brussels as farmers thronged the city's European quarter for the third time in two months, setting fire to tyres and bales of hay, and throwing eggs at riot police.

"We have listened to our farmers and we have taken swift action to address their concerns at a time when they are confronted with numerous challenges," said David Clarinval, deputy prime minister of Belgium, which holds the rotating EU presidency.

He said the revision aims to slash red tape for farmers and give them more flexibility complying with green regulations while also "maintaining a high level of environmental ambition".

The committee backed a proposal from the European Commission to change a set of environmental and climate standards that determine whether farmers can receive CAP subsidies.

A key change involves granting leeway to farmers who fail to meet CAP requirements because of extreme weather.

The revision does away entirely with the obligation to leave a share of arable land fallow -- a measure aimed at protecting soils and promoting biodiversity but a major gripe for farmers. But they would still be incentivised to do so.

Member states would have more flexibility to decide which soils to protect and in which season, and allows them to diversify crops as well as rotate them.

And it exempts small farms under 10 hectares (25 acres) from inspections and penalties related to CAP compliance.

Farmers have been mounting rolling protests in countries across the EU, from Belgium to France, Spain, Italy and Poland, over a long list of burdens they say are depressing revenue.

The concessions are being made less than three months before EU-wide elections for the European Parliament. Surveys predict the vote will result in a surge of support for far-right parties that are using farmers' discontent as part of their campaigning.