LONDON, June 29, 2018 (News Wires) - Europe's leaders demanded clarity from Theresa May on her plans for a post-Brexit trade deal as their impatience over the Prime Minister's divided Cabinet became clear. In conclusions swiftly adopted by the leaders of the remaining 27 European Union nations, they called for "realistic and workable" proposals from the Prime Minister. Brussels' chief negotiator Michel Barnier warned that time was short and suggested an extra round of negotiations on Monday to help reinvigorate the talks. Mr Barnier said "huge and serious divergence" remained over issues relating to Ireland and Northern Ireland. The Prime Minister said she hoped a new phase in the Brexit talks would be possible after the publication of the Government's White Paper calling for negotiations to speed up and intensify once the document is published. Details of the White Paper setting out the UK's plans for issues including trade and customs are expected to be thrashed out by Cabinet ministers at next Friday's Chequers away-day. Asked whether the White Paper would provide "realistic and workable" proposals of the kind sought by Mr Barnier, a Downing Street spokeswoman said: "Yes." On the Irish border, the spokeswoman added: "We have never said anything other than it's very challenging. We've put forward our position which is that we don't want to see a hard border returning. "We've also put forward a backstop proposal, there will be a White Paper next month, and we will continue to talk to the EU, the Taioseach and others about it." Mrs May's participation in the European Council summit ended in the early hours of Friday morning after a marathon session on proposals to address the migrant crisis. She warned EU leaders the safety of their citizens would be put at risk if a deal on security co-operation after Brexit was not reached. Leaving the summit in Brussels, she said: "We are going to be publishing our White Paper shortly and I want to see the negotiations accelerating and intensifying thereafter." She urged her counterparts to change the mandate given to their negotiators in order to allow UK involvement in key law enforcement initiatives allowing police and security agencies to share information. Without a deal she told her counterparts "we would no longer be able to share real-time alerts for wanted persons, including serious criminals" and "our collective ability to map terrorist networks across Europe and bring those responsible to justice would be reduced".