PENNY Mordaunt has warned the EU that Britain “cannot keep negotiating forever” on a post-Brexit trade deal as she prepares this week for another showdown with Brussels.

The UK Government’s Paymaster General will join her Cabinet Office colleague Michael Gove to press Whitehall’s case at the UK-EU Joint Committee on Friday when they will make clear to their continental counterparts that there is no way Britain will extend the transition period beyond December 31.

A deadline of the end of June appears now to have been erased but UK ministers are still trying to instil a sense of urgency in the process, saying they want a “political understanding” with the EU by the end of July to give businesses time to prepare for the new post-Brexit relationship. It comes as some in Brussels have pointed to securing a final deal as late as the autumn.

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A meeting between Boris Johnson and Ursula von der Leyen, the President of the European Commission, is expected in the next two weeks to try to unblock the impasse, which has stalled the talks for months; one of the main obstacles to progress has been disagreement over fishing rights.

Answering an Urgent Question in the Commons from Labour’s Rachel Reeves about the fourth round of Brexit talks, Ms Mordaunt sought to offer assurances that Britain's supply chains would hold up should no trade deal be agreed with the EU.

"We have the Covid crisis going on, I know she is aware of the huge amount of work that was done last year on no-deal preparations but also the tremendous work that civil contingencies and all Government departments have been doing to ensure that supply chains remain strong, that we can quickly adapt, that we do have stocks of all sorts of goods - including medicines - that we need.”

Ms Mordaunt went on: "We cannot keep negotiating forever, we have to allow our businesses, our farmers, our citizens time to implement the decisions taken.

"And that is why we are at this key stage now where we have to increase and escalate negotiations because we need to arrive at a deal soon."

The minister repeatedly ruled out extending the transition period beyond December this year and pressed the need for the UK to be treated as a "sovereign equal".

Her Tory colleague Jerome Mayhew asked Ms Mordaunt if an extension of the transition period would "serve no useful purpose" other than to cost the UK money, prolong business uncertainty, "delay effective control of our borders" and hamper the response to the Covid-19 crisis.

She replied: "The honourable gentleman is damn right."

Ms Reeves said the task was to build the "best possible new relationship" with the EU and agreed the negotiations need to be concluded in good time before warning: "Currently we're in the dark about what this new relationship looks like."

The Shadow Cabinet Office Minister also noted how warnings had emerged about the impact of Covid-19 on medicine stockpiles, saying: "We urge both sides to redouble efforts over the next few days and weeks to ensure progress is made by the end of this month so the Government can honour its commitment to ensuring a good deal for Britain by the end of this year."

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Pete Wishart for the SNP mocked the Government for blaming the EU over an inability to reach a trade agreement.

"It's going to be misery heaped on misery as Covid and Brexit appear like the twin horsemen of the economic apocalypse trampling over any prospect of a recovery.

"And whose fault is it going to be? Obviously, them; nothing to do with us guv', it's all these nasty, invidious Europeans, how dare they hold this Government to the commitments they've already given in good faith? These fiendish Europeans asking us to deliver on what we've already agreed to," said the Perth MP.

The Liberal Democrats’ Alistair Carmichael also decried the Government’s refusal to extend the transition period.

The MP for Orkney and Shetland said: "Food shortages, medicine shortages, and an unprecedented hit to jobs and livelihoods; that is what the UK is facing if we crash out of the EU without a deal.

"Boris Johnson's ideological stubbornness will see the most vulnerable in our country hit hardest,” declared Mr Carmichael.

"With the country is already struggling as a result of Covid-19, it beggars belief that the Government are happy to pile Brexit on top of this already devastating situation.

"Liberal Democrats will continue to urge the Government to think again and extend the transition period," he added.