The UK and EU are still at odds over citizens' rights and the amount the UK will pay to leave the bloc, at the end of the second week of Brexit talks.
EU negotiator Michel Barnier said the UK had not been clear enough about where it stands on these issues and that was hampering progress.
UK Brexit Secretary David Davis said the negotiations on the so-called divorce bill had been "robust".
He said progress had been made but both sides needed to show "flexibility".
Mr Barnier said: "We require this clarification on the financial settlement, on citizens' rights, on Ireland - with the two key points of the common travel area and the Good Friday Agreement - and the other separation issues where this week's experience has quite simply shown we make better progress where our respective positions are clear."
Source : http://www.bbc.co.uk/news/uk-politics-40662740