The UK has called for fresh thinking from the European Union and hit out at “risible” proposals on fishing quotas amid mounting tensions as both sides enter what could be the final week of post-Brexit trade negotiations.  

There was anger on the UK side after reports emerged the EU could accept just a 15-18 per cent cut in its share of fishing rights in UK waters, emphasising how far away from a deal the talks are.  

The UK, led by chief negotiator Lord Frost, is understood to believe that the potential benefits of a no-deal Brexit are underappreciated, despite dire warnings of the effect on businesses and the economy.    

A source close to the negotiations said the UK was not going to “sell out” its sovereignty.  

They said: “Over the coming days we will continue to negotiate with creativity and intensity. We hope that the EU will come with some fresh thinking because what we’ve seen so far doesn’t cut it. They must understand that we are not going to sell out our sovereignty.”

A government source added: “These figures (on fishing) are risible, and the EU side know full well that we would never accept this. There seems to be a failure from the Commission to internalise the scale of change needed as we become an independent nation.”

However, it is understood that a potential path has emerged that could pave the way for agreement on one of the other main sticking points, the level playing field.  

Face-to-face Brexit negotiations have resumed in London, with just over a month before the transition period ends on 31 December.  

But there is thought to be growing scepticism among other EU states about the prospects of a deal.  

Home Secretary Priti Patel suggested UK ministers were still prepared to walk away even at this late hour.  

The government was committed to ensuring the Brexit talks were “conclusive”, she said.  

“But at the same time we are preparing in the way in which our country would expect us to prepare for the end of transition.”  

Earlier, French MEP Pierre Karleskind, who chairs the European Parliament’s fisheries committee, defended the fishing proposal.  

He told BBC Radio 4’s Today programme: “You asked for your companies to access the common market of the European Union, and we ask our fishermen to access your waters…it is reciprocity.”

On Friday Lord Frost said that any deal must respect the UK’s sovereignty.  

“That is not just a word – it has practical consequences. That includes: controlling our borders; deciding ourselves on a robust and principled subsidy control system; and controlling our fishing waters.”

Boris Johnson also underlined his commitment to reaching a Brexit deal that respects the sovereignty of the UK in a call with Irish prime minister Micheal Martin.

The UK government is understood to believe a crunch point in the talks, when it will become clear if a deal can be struck or not, may come within days.  

Chaos is predicted at British ports whether or not a deal is struck.  

However, a no-deal is expected to do more damage to the British economy.