Food and drink manufacturers, retailers and farmers have called on Theresa May to ensure they continue to enjoy tariff-free trade with the European Union after Brexit.
The British Retail Consortium, the National Farmers Union and the Food and Drink Federation also called for transitional arrangements to maintain "frictionless" trade in goods and avoid "costly and disruptive" customs controls.
The industry employs 3.9 million and is worth £108 billion to the UK and "cannot operate in isolation", according to the coalition of trade bodies.
In a joint statement to ministers at the Government departments for Brexit, International Trade, Environment and Business, the group said much of the food supply chain is based domestically.
But they pointed out that farmers need to import feed and export products where UK demand is insufficient, that manufacturers rely on exports to grow their businesses and imports for some ingredients, and retailers need access to a "full range of goods" to meet consumer demand.
As the Prime Minister prepares to trigger Article 50 to begin the exit process on Wednesday, the coalition also called on the Government to:
::Secure the benefits for UK traders of existing EU preferential trade arrangements, including the UK's fair share of tariff rate quotas for agricultural imports, as well as of any preferential access for UK food and drink exports, at least until ministers can replace them with acceptable alternative arrangements.
::Establish cooperation with non-EU countries on equalising regulations and ensuring that all new trade agreements take into consideration differences in regulations and standards when market access is negotiated.
::Ensure detailed economic impact assessments are carried out when trade negotiations are opened and before offers are exchanged.
A Government spokeswoman said: "We are determined to get the best deal on leaving the EU - including for our world-leading food and drink industry. Securing a bold and ambitious free trade agreement with our European partners is a priority - allowing for the freest possible trade in goods and services.
"At the same time, we are going to make the most of the opportunities that our departure presents - getting out into the world and doing business right across the globe."