The UK still believes it can agree a post-Brexit trade deal with the EU next month, according to Downing Street.
The PM’s spokesman said UK negotiators would “continue to plug the gaps” as negotiations enter their seventh round in Brussels on Tuesday.
The two sides remain divided over competition rules, fishing rights and how a deal would be enforced.
The UK has ruled out extending the December deadline to reach an agreement.
This week’s talks are the last scheduled negotiating round ahead of the autumn, although both sides have previously said talks would continue in September.
After the last round in London, EU chief negotiator Michel Barnier said the UK had not shown a “willingness to break the deadlock” over difficult issues.
He added that an agreement would be needed by October “at the latest” so it could be ratified before the current post-Brexit transition period ends in December.
His UK counterpart David Frost said EU offers to break the deadlock had failed to honour the “fundamental principles which we have repeatedly made clear”.
But he said the UK, which has so far insisted on a series of separate deals in different areas, was also willing to consider a “simpler” structure for an agreement.
He added the EU had shown a “pragmatic approach” over British demands to limit the role of the European Court of Justice after the transition period ends.