Welsh farm leaders have said a UK-EU trade deal which allows tariff free access to European markets is 'critical to the survival' of farmers in the country.
Farming unions and organisations have written an open letter to Boris Johnson urging the government to avoid a no-deal following the Brexit transition period.
The nine groups say key issues must be 'addressed immediately' as the EU is the largest market for Welsh food and farming businesses.
Agricultural exports to the bloc such as red meat and dairy products are worth an estimated £350 million to Wales, they highlight.
In 2018, 73 percent of all Welsh food and drink exports were destined for the European Union.
The Welsh sheep sector relies heavily on the EU market. Over a third of sheep meat is exported annually and, of this, more than 90% is to the EU.
The letter also states that the Protected Geographical Indication (PGI) status of Welsh Lamb and Welsh Beef are of 'enormous economic importance' to farmers.
Organisations which signed include the Farmers’ Union of Wales (FUW), the National Beef Association, NFU Cymru and the National Sheep Association Cymru.
"As an industry in Wales, we are committed to working with you to support this process," the letter, addressed to the prime minister, says.
"However, whilst new market opportunities may emerge in the future, the impact of ending the withdrawal period without a comprehensive UK-EU trade deal would be catastrophic and we cannot emphasise strongly enough the need to avoid this outcome.
"A trade deal allowing tariff free access to the EU market must be reached if acute and longlasting damage to our industries is to be avoided."
The groups call for a six-month grace period negotiated and agreed with the EU to allow businesses to adjust to the impacts of the new rules which would be in place for exports.
Efforts to reduce the impacts of non-tariff barriers must be stepped up, they say, both in terms of the actions that can be taken unilaterally by the UK and what is negotiated with the EU.
“The European Union is the largest market for Welsh food and drink businesses to export their goods to,” said FUW President Glyn Roberts.
“What happens in the run up to 1 January 2021 is critical to the economic viability of many food, drink and farming businesses and the supply chains and jobs they support."
What do the organisations want?
The open letter highlights six actions the farming groups believe are essential in the coming weeks, namely:
• A trade deal allowing tariff free access to the EU market
• A six-month grace period to allow businesses to adjust to the impacts of the new export rules
• Efforts to reduce the impacts of non-tariff barriers
• The food and drink sector must be added to the Shortage Occupation List
• Appropriate physical infrastructure and staffing at UK ports must be in place at the end of any transition period
• Financial assistance packages for food and drink producers must be put in place ahead of any changes to trading arrangements
