The European Council president Donald Tusk says he is not hopeful of progress on a Brexit deal ahead of a crunch summit of EU leaders.
Agreement on a backstop to prevent a hard border in Northern Ireland remains the main sticking point.
Mr Tusk says there needs to be creativity from Theresa May when she addresses EU leaders in Brussels.
The EU wants an 'all weather' guarantee from the UK to ensure a hard border will never be imposed.
This week's summit had been billed as the deadline for agreement, but talks may now run into November or December.