Britain is unlikely to make “sufficient progress” in Brexit talks until the end of the year, the European Council President has said.

Speaking in Brussels on Tuesday, Donald Tusk also warned that if negotiations continued at the current “slow” rate then both sides would have to “think about where we are heading”.

Both the UK and EU have previously said they wanted to reach the milestone – as set and judged by the EU – by October this year, with officials saying as recently as last month that they were “optimistic” it could be met.

When the European Council deems sufficient progress on separation issues like the divorce bill, Northern Ireland border, and EU citizens’ rights to have been met, it says it will authorise its negotiators to move on to other issues like trade and the future relationship with the UK.

However Mr Tusk has now said he believes his institution will not judge sufficient progress to have been made until at least December – and has hinted that at the current rate of progress it may never be reached.

“We hear from London that the UK Government is preparing for a ‘no deal’ scenario. I would like to say very clearly that the EU is not working on such a scenario,” he told the European Committee of the Regions.

“We are negotiating in good faith, and we still hope that the so-called sufficient progress will be possible by December.

“However, if it turns out that the talks continue at a slow pace, and that ‘sufficient progress’ hasn’t been reached, then – together with our UK friends – we will have to think about where we are heading.”

The President also used his address to warn that while “Britain’s referendum campaign was full of false arguments and unacceptable generalisations” it “would have been a big mistake to interpret the negative result exclusively as a symptom of British exceptionalism and Euroscepticism”.

“All over Europe, even moderate voters were asking ‘is the European Union the answer to problems of instability and insecurity, or is it now standing in the way?’” he admitted.

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The fifth round of talks are currently under way in Brussels, with the next official update due on Thursday.

A UK Government spokesperson said: "As the PM said yesterday, we have made real and tangible progress in a number of vital areas and we are looking for the negotiating teams to reach full agreement quickly.

"We are approaching these negotiations in a constructive way and in a spirit of friendship and cooperation.