The president of the European Parliament has dismissed the UK's series of position papers on Brexit as not being satisfactory, insisting there will be no progression to trade talks until the EU is happy with the divorce deal.
"The UK government is hesitant in showing all its cards," Juncker said. "Why would it do this? We now have the negotiating team in Brussels meeting with Mr Barnier. I did read with the requisite attention all the papers produced by Her Majesty's government. But none of those papers are in fact satisfactory."
Juncker, who was speaking as the third round of talks begin in Brussels, added: "There are still an enormous number of issues that need to be settled. Not only the border problems with Ireland and Northern Ireland, which is a very serious problem to which we have had no definitive response, but also the issue of European citizens living in the UK and UK citizens living on the continent.
"We need to be crystal clear that there will be no negotiations, particular on trade between the UK and the EU, before all these issues, that is to say those under Article 50, are resolved. That is to say the divorce between the EU and the UK."
Prime ministers of Slovenia and Ireland have already indicated that this would be the case, however Barnier has stopped short of confirming that would be the case.
The City is desperate to hear details of a transitional deal, warning that the financial district must have clarity by the end of the year to avoid triggering a Brexodus of nervous firms.
Update: A Downing Street spokeswoman insisted the UK was in a "good position" to be able to "move on to discuss our future relationship".
She added: "As David Davis has said, we believe that we need the EU to show some more imagination and flexibility when it comes to these discussions ... Our desire is to discuss both [withdrawal and trade] at the same time.