European Council president Donald Tusk has demanded more clarity from Prime Minister Theresa May over her plans for Brexit - and again held open the possibility of the UK changing its mind.
Addressing MEPs in Strasbourg, Mr Tusk said: "If the UK Government sticks to its decision to leave, Brexit will become a reality - with all its negative consequences - in March next year unless there is a change of heart among our British friends.
"Wasn’t it David Davis himself who said ’If a democracy cannot change its mind, it ceases to be a democracy’?"
Mr Tusk insisted that the EU had not had a "change of heart" over Brexit, telling the British: "Our hearts are still open for you."
Responding to the Council president’s comments, Theresa May’s official spokesman said: "We have been absolutely clear that the British people voted to leave the European Union and that is what we will be doing."
Calling for continued unity among the remaining 27 members of the EU, Mr Tusk said: "The hardest work is still ahead of us and time is limited.
"We must maintain the unity of the EU27 in every scenario, and personally I have no doubt that we will."
Mr Tusk’s comments came as a leaked European Commission paper suggested the EU is toughening its stance on the transition period after the official date of Brexit in March 2019.
A document obtained by The Guardian suggested the EU will insist on free movement of people throughout the period, and permanent rights to settle for any EU nationals moving to the UK before the end of 2020.
Chief negotiator Michel Barnier is also set to insist that the UK will have to seek "authorisation" from Brussels to continue enjoying the benefits of the bloc’s existing trade agreements with non-EU countries, the paper suggests.
The December European Council had agreed that "sufficient progress" had been made on the first phase of Brexit talks, allowing negotiations to move on to consider transition and a future deal.