Bord Bia has calculated that the fall in the value of sterling following Britain's Brexit vote cost Irish food and drink exporters €570m last year alone.
In its annual Export Review and Prospects Report, the agency warns that exports markets for Irish food and drink will continue to be challenging this year and that prepared food exports to the Britain will remain under pressure.
Overall, the value of Irish food and drink exports grew by 2% last year to a total of €11.15bn.
It was the seventh consecutive year of growth, but Bord Bia's report highlights just how big, and how negative, an impact Brexit has had on Irish food exports in the past six months.
Overall, Irish food and drink exports to the UK fell by 8% last year, which Bord Bia attributes to weaker sterling.
Cheese exports to Britain, which accounts for half of all Irish cheese exported, showed a double-digit percentage decline, while mushroom exports were decimated.
The UK had accounted for 41% of Irish food and drink exports in 2015.
That is down to just 37% on foot of the decline in sterling since the Brexit vote.
Bord Bia is warning that export markets for Irish food and drink will continue to be challenging throughout 2017.
The Minister for Agriculture, Food and the Marine this morning said he has met with the chief executives of Tesco and Sainsbury's in the UK and held meetings with his British counter part, Andrea Leadsom, in order to help navigate the difficulties that Brexit poses to Ireland's food and drinks industry.
Michael Creed pointed out that Bord Bia exports to 180 countries around the world and that efforts were being made to increase markets.
He said access to the Egyptian market for beef exports was opened last week.
The minister said that he is working with the mushroom industry to try to navigate what is a very difficult industry but that things looked strong for the dairy market in the year ahead.
Brexit will present major challenges for agri-food sector
In the UK, a meeting of the Commons Northern Ireland Affairs Committee has been told that Brexit will present major challenges for the agri-food sector.
Representatives of a number of agri-food agencies told the committee that anything which would hinder free cross border movement would have an adverse effect on trade.
The committee was discussing the post-Brexit future of the land border between the Republic and Northern Ireland.
NI Director of Dairy UK Mike Johnson the told the meeting that the dairy industry was very dependent on 'an all island value chain' because over decades the industry had developed methods of working together - North and South - to deliver efficiency and productivity.
Mr Johnson said any interruption in those practices was critical.
He said that if there was not freedom of movement of product then Northern Ireland would not have the capacity to handle the current volume of milk.
As such, he added, either dairy farmers in the North would go out of business or sufficient transition time would be needed to invest in new processing facilities in Northern Ireland.
Ulster Farmers Union President Barclay Bell said that the current political crisis at Stormont was also concerning.
He said that just at a time when stable government was needed to represent Northern Ireland's needs in terms of Brexit, they were stepping into the unknown.
UFU Deputy President Wesley Aston said Brexit could provide opportunity, suggesting it could mean that Northern Irish farmers might access the UK market better than they currently do.
He said it should be done anyhow, but, in the event of Brexit, it would be one of the markets which could be explored.