The EU Council president railed against the “false arguments and unacceptable generalisations” of the referendum campaign but said the bloc was committed to making the best of Brexit.
In a keynote speech the Polish eurocrat said europhiles would be wrong to interpret the vote as “exclusively British exceptionalism” and instead needed to address widespread concerns about the project.
And he insisted the challenge of conducting the Brexit talks had “shown the EU at its best in terms of unity, political solidarity and fairness towards the United Kingdom”.
Mr Tusk’s comments came after Theresa May told the British parliament that she was setting up a new crack team of civil servants to work towards the possibility of a no-deal exit.
The PM has always stood behind her assertion that “no deal is better than a bad one”, despite the fact it has angered some domestic politicians and many of her European counterparts.
Yesterday she told MPs the Government wanted to secure a good trade deal with the EU, but that it did not anticipate achieving such an outcome until “close to the end” of any transition period.
She added: “While I believe it is profoundly in all our interests for the negotiations to succeed, it is also our responsibility as a Government to prepare for every eventuality, so that is exactly what we are doing.”
For its part, Brussels has always insisted it is not countenancing the possibility of the UK leaving without an agreement and has previously refused to confirm whether or not it was putting contingency plans in place.
But addressing the Committee of the Regions today, Mr Tusk revealed: “I would like to refer to Prime Minister Theresa May’s recent words. 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. 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.”
His conciliatory comments will be interpreted as the EU effectively trying to take a no-deal exit off the table and are likely to come as a significant boost to British negotiators.
Elsewhere in his speech the Polish official, who chairs meetings of the EU member states, decried the Brexit referendum campaign which he said was “full of false arguments and unacceptable generalisations”.
However, Mr Tusk also acknowledged that it “would have been a big mistake to interpret the negative result exclusively as a symptom of British exceptionalism and Euroscepticism” rather than wider European malaise.
He said: “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?’.
“I am now in the middle of these consultations, whose main aim is to provide real solutions to real issues of concern for our citizens, inter alia unemployment, irregular migration, fears connected with globalisation, and, of course, still Brexit.”