BRUSSELS is set to intensify the row over Brexit and fishing rights at this weekend’s EU summit after a leaked document revealed the EU27 wants to “build on” the current access arrangements loathed by UK fishermen.

The leak came as campaign group Fishing for Leave dismissed Theresa May’s strong insistence that there would be “no trade-off” between EU access to UK waters post Brexit and Britain’s desire to get a trade deal with the EU27, accusing her of being either “an idiot or a liar” over her assurance.

The leaked one-page EU paper points out how the desire to get a fisheries agreement by July 2020 must protect the existing rights of European fishing fleets to use British waters.

And it warns that a failure by the UK Government to endorse this could risk any hope of extending the transition period; this is the option being considered by the Prime Minister as a means of avoiding the need for the highly contentious Irish backstop guarantee to keep the border with the Republic open should a trade deal not be agreed by December 2020.

The leaked paper says the EU “will demonstrate particular vigilance on the necessity to maintain ambitious level playing field conditions and to protect fishing enterprises and their communities”.

It is thought that the insertion of this line was demanded by France as a warning to Britain that it could not renege on its promises during future trade talks.

The paper then says: “As recalled in the Withdrawal Agreement, a fisheries agreement is a matter of priority and should build on, inter alia, existing reciprocal access and quota shares. Such an agreement will be negotiated before the end of the transition period.”

The EU27 document adds: “Any decision on the extension of the transition period will take into account the fulfilment of obligations by the United Kingdom under the agreement, including its protocols.”

The Department for Environment, Food and Rural Affairs has said the inclusion of such language in the political declaration was explicitly rejected, stressing how there was no commitment to maintain existing EU access to UK waters.

During her Commons statement on Thursday, the PM told MPs: “We have firmly rejected a link between access to our waters and access to markets.

“The fisheries agreement is not something we will be trading off against any other priorities. We are clear that we will negotiate access and quotas on an annual basis, as do other independent coastal states such as Norway and Iceland.”

David Mundell, the Scottish Secretary, has been equally adamant that there would be no trade-off between EU access and UK trade.

Yet Nicola Sturgeon, the First Minister, accused the UK Government of “selling out” Scottish fishermen while her colleague Ian Blackford, who leads the SNP at Westminster, accused the PM and her colleagues of using UK fishing rights as a “bargaining chip” in talks with the EU towards securing a fishing agreement by the summer of 2020 before the transition is due to end in December of that year.

Indeed, Scottish Conservative MP Ross Thomson, who represents Aberdeen South, said of the UK-EU political declaration that “sovereignty over our waters sacrificed for a trade deal".

Scottish Tory MPs have been particularly forceful in seeking assurances from Mrs May about the Brexit process and fishing with Mr Mundell signalling he would resign if any transition period extension kept Scottish fishermen tied to the hated Common Fisheries Policy.

On Friday, No 10 pointed out how Mrs May had been “very strong” on the point of fears over a trade-off between EU fishing access and Britain’s desire for a post-Brexit trade deal.

“The PM said we are going to become an independent coastal state and rejected a link between access to our waters and access to markets and the agreement is not something we are going to trade off against any other priorities.”

Mrs May’s spokeswoman knocked back any suggestion of an addendum to the Withdrawal Agreement or Political Declaration to offer a side deal. She said: “The PM set out exactly what the agreement means for fishing and that is our position.”

Meanwhile, Fishing for Leave claimed that Protocol Article 6 of the Withdrawal Agreement ran a “coach and horses” through ministerial promises, declaring: “The Government has already flagrantly capitulated on markets and access being linked by agreeing to Article 6.”

Referring to the single customs territory, this says that fishery and aquaculture products will “not be covered…unless an agreement on access to waters and fishing opportunities is applicable between the Union and the United Kingdom”.

Fishing for Leave added: “The Government has therefore, in breach of all promises, already agreed that unless the UK cough up access for EU boats to continue fishing in British waters, then the EU will deny access for fisheries and aquaculture products.

“The PM saying this is not the case at the dispatch box...means she’s either an idiot or a liar.

In response, a UK Government spokeswoman said: "We’ve been clear that we will be an independent coastal state after we leave the EU. Throughout this process we have successfully resisted attempts from the EU to secure access to UK waters on current terms. This demonstrates the Government’s firm commitment to the future of our fishing industry.

"We are clear that there will be no guarantees on access to our waters once we leave the Common Fisheries Policy. The Political Declaration explicitly commits both parties to use their ‘best endeavours’ to ensure a new fisheries agreement is in place by July 1 2020. This will provide a framework for us to meet annually to determine both access and quotas consistent with international precedents, such as Norway and Iceland."