Protesters poured green paint outside the EU Parliament, holding banners criticising the plan to change the bloc's Common Agricultural Policy (CAP).
EU negotiators began two days of talks on Tuesday (May 25) on a plan designed to make the bloc's huge farming subsidies greener and fairer, although campaigners question its environmental impact.
The CAP will spend 387 billion euros ($473 billion), around a third of the EU's 2021-2027 budget, on payments to farmers and support for rural development, with new rules kicking in from 2023.
The revamp aims to align agriculture with the EU's target of zero net emissions by 2050, by tackling the 10% of EU greenhouse gases emitted by farming.
The proposed changes have come under fire from environmental campaigners, who say they lack firm targets and would allow the bulk of subsidies to be spent on polluting forms of industrial farming.
The latest proposal would set aside 23% of payments to farmers from 2023 for schemes that safeguard the environment, and 25% from 2025 onwards. That could include organic farming or the use of feed additives to reduce methane emissions from cows.
Negotiators are also tussling over how to ensure the CAP supports small farmers.