Clarity is urgently needed about "every aspect" of the future relationship between the European Union and the United Kingdom, Dutch Prime Minister Mark Rutte said after meeting British Prime Minister Theresa May.
"We urgently need clarity about every aspect of the future relationship between the EU and the UK," he said.
Mrs May, meanwhile, has called on her Conservative party to "stand together" over Brexit, days before a crunch meeting she hopes will overcome bitter rifts over how Britain should leave the European Union.
Britain's exit from the bloc will mark its biggest trading and foreign policy shift in almost half a century.
But Mrs May has struggled to unite her cabinet and party - or parliament and the public - around a plan, often reluctant to spell out her approach for fear of angering one faction or another.
It is unclear what Mrs May will present to her cabinet at the away-day meeting in Chequers on Friday, but those wanting a "clean break" with the EU fear she will try to force them into a compromise on customs that will keep Britain firmly in the bloc's sphere, as desired by some companies and several members of her cabinet.
At a meeting of her top ministers this morning, Mrs May said she "looked forward to the full discussion which will take place at Chequers on Friday, when decisions will be taken on the future partnership the UK is seeking with the EU".
But yesterday, Mrs May appealed to her party at aConservative fundraising event not to allow the scale of the Brexit challenge to "overwhelm us".
"The stakes are high. Perhaps higher than we have ever known in our political lifetimes. We each have a choice to make," she said at the fundraiser, according to her office.
"Will we come together and stand together as a party, as a government and as a country? ... Or will we be divided and allow the scale of the challenge, the complexity of the questions to overwhelm us?"
Mrs May is under pressure from businesses in Britain and EU officials to come up with a workable plan for Brexit, one that allows trade to continue unhindered and prevents a hard border on the island of Ireland.
But eurosceptics in her party are determined to keep Mrs May to her word that Britain will leave the EU's single market, customs union and the jurisdiction of its court in March next year. They warn against any betrayal of the June 2016 referendum vote to leave the EU.
"At Chequers the prime minister must stick to her righteous cause and deliver what she has said she would do," Conservative Brexit campaigner Jacob Rees-Mogg wrote in The Sun today.
Foreign Secretary Boris Johnson tweeted: "It's vital that all MPs are able to air their views on Brexit."
European Commission president Jean-Claude Juncker told MEPs in Strasbourg: "We have been waiting for months now for the White Paper from No 10 Downing Street and we will analyse it once we receive it.
"We will not accept that the Irish issue is isolated in such a way that it is the only issue not resolved at the end of these discussions."
European Council President Donald Tusk said said there is a lot of work yet to do with less time and the sooner there is a UK proposal on the Irish border, the better.
He also said a "solid backstop" was required and had to be accepted by the European Union's "Irish friends".
He said clarity and realism were required in the negotiations
