Brussels was last night told to 'get real' and start treating the UK as an independent state if it wants to seal a post-Brexit trade deal.

Boris Johnson issued a stark warning that major obstacles remained in talks with the EU, and time was running out to clinch an agreement.

But the Prime Minister faced his own warning that avoiding No Deal was his best chance of having a good relationship with newly elected US President Joe Biden.

EU negotiator Michel Barnier arrives in London today for a fresh round of intensive talks with his opposite number, Lord Frost, with the Brexit transition date of December 31 fast approaching.

Mr Johnson has warned European Commission president Ursula von der Leyen that despite some progress, 'significant differences' remained between the two sides over state aid and fishing.

They both agreed their teams would 'redouble their efforts to reach a deal', but in strongly worded comments, UK sources said unless Brussels changed its approach and accepted the UK's newly restored status as an 'independent state', a deal was in jeopardy.

Progress had been made on several issues, but a source said: 'Unfortunately, we haven't achieved as much as we'd hoped during these intensive talks so far. We still need more realism from the EU.

'They can't expect us to agree to a treaty under which we can't move away from EU norms in important areas. And they don't seem to have realised the scale of change in fishing rights they face if there is no agreement.'

UK negotiators are understood to be frustrated by what they see as Brussels' failure to move on the key issue of fisheries despite the fact that without a deal, EU countries would lose all fishing rights in UK waters. 

They said Mr Barnier had told EU ambassadors that Brussels wanted free access to UK waters and continuity in fish catch quotas – a position dismissed as 'not reasonable or realistic'.

A source said: 'It's a shame this is having to be done so quickly because of the EU's foot-dragging until very recently.

'And there is still a long way to go; a deal is by no means certain unless we see a change of approach from Michel Barnier and his team.'

Sir Nigel Sheinwald, a former British ambassador to the US, made clear yesterday that pro-EU Mr Biden's victory made it all the more important Mr Johnson got a deal with Brussels. 

In a letter to The Times, he wrote: 'After a Biden victory and a failure to reach a trade deal with the UK, Britain would occupy a lonely place in the world.

'Hence, Johnson should get the UK/EU post-Brexit deal done as quickly as possible.'