The UK faces losing free trade agreements with more than 70 non-EU countries in the event of a no-deal Brexit.
The warning came as the government released the last batch of technical papers outlining scenarios and preparations in the event of a no deal Brexit agreement.
The countries – which account for 12% of the UK’s total trade – are covered by around 40 EU free trade agreements delivering preferential tariffs and enhanced market access.
A total of 104 such papers have now been released by the Department for International Trade (DIT).
New guidance covers areas ranging from the regulation of pesticides, trading in electricity, rail transport and consumer rights, while another warned that the UK export trade in rough diamonds could be totally halted by a no-deal Brexit.
Brexit Secretary Dominic Raab said: “We have now published over 100 technical notices, giving individuals, businesses, public bodies and NGOs (non-governmental organisations) information and guidance in the unlikely event of no deal.
“Securing a good deal with our EU partners remains our top priority. But, if the EU doesn’t match the ambition and pragmatism we’ve showed, we have the plans in place to avoid, mitigate or manage the risk of no deal – and make a success of Brexit.”
But shadow Brexit secretary Sir Keir Starmer said: “The Government’s no-deal planning won’t reassure anyone. Ministers have barely scratched the surface of what would need to be done in the event of the UK crashing out of the EU without a deal.
“Despite all the so-called no-deal planning, the Government has yet to admit that a no-deal would require a raft of substantial legislation to be rushed through Parliament, crucial stop-gap agreements with the EU on matters relating to Northern Ireland and security, and the recruitment of thousands of customs officials. None of this is going to be done or ready by March 2019.
“The truth is the only reason the Tories are talking about no-deal is because their civil war on Europe has put any chance of a good deal for Britain at risk. It’s time ministers stopped arguing with themselves and put the national interest first.”
DIT said that, in its preparations for Brexit, it is seeking to forge new bilateral deals with the 70 countries currently covered by EU trade agreements which will be “identical or substantially the same” as the arrangements which Britain is giving up.
But it warned companies that, even if such deals can be reached, there may be “practical changes” to the way trade takes place, depending on discussions with each individual country.
And it confirmed that if these are not in place in time for a no-deal Brexit, exports and imports to these countries will become subject to tariffs under World Trade Organisation rules.