The Ulster Farmers' Union has said it will take part in a demonstration in Westminster urging the UK Government to maintain strict standards on food following Brexit.
UFU president Ivor Ferguson said it and unions from England, Wales and Scotland are planning to stage a demonstration in March.
UFU chief executive Wesley Aston said that the UFU is also concerned that while the Ireland and Northern Ireland protocol in the Brexit withdrawal agreement enables farmers here to trade into the Republic and the EU, the process presented barriers to trade in Britain - Northern Ireland's biggest market.
And with NI farm products made to adhere to EU standards in future, farmers could find it harder to trade into Britain, if standards there are different in future.
Mr Ferguson said that with farmers here operating to strict Red Tractor standards - which impose levels of animal welfare - it could face competition from cheaper goods in Britain if standards were lowered.
Mr Ferguson said the UFU and other unions had been lobbying for food standards to be maintained in the UK following Brexit. "Theresa Villiers (Environment Secretary) will say that of course we're going to keep out hormone-treated beef and chlorinated chicken, but that's only part of the problem.
"We want to make sure that if a deal is being done they have to match Red Tractor standards as a minimum. That takes in animal welfare and all these other things, and that would protect us.
"We have been campaigning and lobbying hard on this and we haven't had any comfort yet.
"We hope to go to set up a demonstration on behalf of the four unions going forward, just to highlight the concerns to the Press and the consumers."
While the Brexit withdrawal agreement provides for "unfettered access" to the British market from Northern Ireland, Mr Aston said he was concerned about how that would operate in practice. "There's always been concerns about both the genuine commitment to that and also about Great Britain to Northern Ireland." Mr Aston said that with a deadline of the end of the year imposed by the Prime Minister for securing a free trade agreement, that could mean a deal reached in a short period could be closer to the existing state of affairs. But he added: "Equally, the Chancellor came out the other day and said businesses need to wise up and realise that they need to do things differently after Brexit. So the two don't necessarily add up, so we have real concerns about NI trade in the UK internal market."