The UK could be required to follow new rules implemented by the European Union during a Brexit transition period according to leaked plans reportedly drawn up by Brussels' chief negotiator.
The position set out by Michel Barnier would make the application of new EU rules a condition of a transitional deal, meaning Britain could be subject to further Brussels' regulations for about two years after leaving the bloc.
Theresa May hopes to secure an implementation period between the UK's formal exit date and the commencement of any post-Brexit trade deal in order to give businesses time to adjust to the new arrangements, but accepting the imposition of new rules could trigger a revolt by Eurosceptics.
It would also go against the approach to an implementation period set out by the UK Prime Minister in her Florence speech, where she said the "framework for this strictly time-limited period ... would be the existing structure of EU rules and regulations".
But the Independent obtained a presentation drawn up by Mr Barnier for representatives of the 27 remaining EU members which said a transitional deal would involve the "automatic application in the UK of new EU rules post-30 March 2019".
It also makes clear that after leaving the bloc the UK would have "no institutional rights, no presence in the institutions" and "no voting rights" - indicating that the UK would have no say over rules it would have to implement in the period.
UK Foreign Secretary Boris Johnson has already indicated that accepting further regulations from Brussels would cross a red line.
He told the Sun in September: "You heard the Prime Minister say very clearly in Florence that she envisages the transition period being run under existing arrangements - that was the phrase she used, 'The existing rules'."
The Prime Minister wants talks on a trade deal and an implementation period to be given the green light by EU counterparts at the European Council on December 14-15.
But she has been warned by European Council president Donald Tusk that while that was possible it would be a "huge challenge".
He has given her until December 4 to make progress on issues including the Brexit divorce bill and the thorny problem of the Irish border.
Meanwhile the UK and EU's plans to share out quotas for cheap food imports from countries around the world after Brexit have come under fire from Australia.
Restrictions on how many products can be imported into the EU on favourable rates are set across the bloc and concerns have been raised internationally that exporters could take a financial hit when the UK quits.
The government has agreed with Brussels to divide up the number of goods that can be brought in on low or zero tariffs based roughly on current rates.
Australian trade minister Steven Ciobo said the move would impose unacceptable restrictions on nations exporting to the bloc.
"The point is that you have a choice about where you place your quota at the moment," he told the BBC.
"Therefore, given that you could put it in the UK or you could put it into continental Europe, why would we accept a proposition that would see a decline in the quota available because of the Brexit decision?"
Other countries with concerns about the quota-splitting plan include the United States, New Zealand, Brazil and Canada.
A UK Department for International Trade spokesman said: " We want to ensure a smooth transition which minimises the disruption to our trading relationships with other WTO members and tariff rate quotas are one of the issues that we are discussing with them.
"This is largely a technical process and we will continue to engage WTO members including Australia in an open, inclusive and transparent way."
Shadow international trade secretary Barry Gardiner said Liam Fox had been warned about the danger of a dispute over the quota share deal.
He also cautioned against accepting higher amounts of low-tariff imports of products such as lamb because of the impact it would have on UK farmers and the countryside.
"We warned the Secretary of State Liam Fox about this a number of months ago and he said this was going to be very easy because it was not going to make any changes in the current total quota that the EU has," he told Today.
Mr Gardiner said the countries raising objections about the quota-sharing plan "have a point" and "this is something that is going to be a tougher negotiation than the Government ever thought".
He added: "We must not look at this simply as a matter of economics. It's not simply about, 'are we going to get cheaper lamb in the UK if we import a lot more from New Zealand?' - the real issue here is what these things do to our wider economy and the landscape of this country.
"As you affect farming, so you affect the way our country looks, that means you also affect the tourist trade."