British Prime Minister, Theresa May, will seek Friday to finally unite her warring ministers behind a Brexit plan and unblock negotiations with the European Union, amid warnings she is running out of time to get a deal.

The lack of progress has frustrated European leaders, who are stepping up preparations in case there is no agreement at all, and businesses who are being increasingly vocal about the risks to jobs and investment.

May hopes to finally settle the issue during a day-long cabinet meeting at Chequers, the 16th-century manor house that serves as her official country retreat, before publishing a detailed blueprint for Brexit next week.

Ministers will have to hand in their phones on arrival for the high-stakes meeting, according to reports.

"The cabinet meets at Chequers today to agree the shape of our future relationship with the European Union," May said in a statement.

During a visit to Berlin on Thursday she said an agreement would "enable the pace and intensity of the negotiations to increase".

May was visiting Chancellor Angela Merkel as part of a fortnight of diplomatic activity ahead of the Chequers meeting, which included talks with the bloc's president Donald Tusk.

Agreeing a common position among her divided ministers is only one element of the Brexit process -- the hardest part will be getting agreement from Brussels, which has repeatedly warned Britain to lower its expectations.

The EU's chief negotiator Michel Barnier said last week he wanted to see "workable and realistic proposals", while Tusk said: "This is the last call to lay the cards on the table."

'This is not Brexit'

Socio-economic indicators comparing the UK with other EU states

Leaked proposals suggest May will propose to keep and commit to future EU rules on trade in goods, an outcome intended in part to fulfil a pledge to avoid customs checks on the border between Northern Ireland and Ireland.

By contrast it will accept "reduced market access" for services -- Britain's dominant sector -- in return for greater flexibility, reports suggest.

The plan caused outrage among eurosceptic MPs in May's Conservative party, with one fuming that "this is not Brexit" and another saying it would leave Britain "out of Europe but still run by Europe".

"This common rulebook means that we are essentially a vassal state," leading eurosceptic backbencher Jacob Rees-Mogg told the Daily Telegraph newspaper.

Seven Brexit supporting cabinet ministers met at the Foreign Office on Thursday to discuss their push back against the plans, according to British media reports.

They are expected to tell May that the leaked details are "not acceptable", warning that she risks bringing the government down, according to the Daily Telegraph, with scores of backbench eurosceptic Tories able to force a confidence vote on her leadership.

They are particularly concerned that alignment on goods would restrict Britain's ability to sign trade deals with non-EU countries such as the United States, which for many is the chief reason for leaving the EU.

May's approach has in the past been publicly challenged by Brexit-backing ministers in her cabinet such as Foreign Secretary Boris Johnson, while Brexit Secretary David Davis has threatened to resign several times.

The question is whether they can accept May's plan as warnings grow that continued in-fighting may prompt a revolt in parliament, where most MPs are against Brexit.

"If they can't decide, it will be up the Commons to take control," one pro-European MP told AFP.