There is “not a moment to lose” if the UK and EU are to reach a Brexit deal, the EU’s chief negotiator has said.
Michel Barnier, speaking ahead of talks with Theresa May and David Davis in London, said he respected the UK’s “red lines”, but EU rules must be respected.
Downing Street earlier insisted Britain will not be in a customs union with the EU, amid claims of Tory disunity.
Mrs May faces calls to spell out more detail of what she wants in talks ahead of the UK’s departure in March 2019.
The prime minister and Brexit Secretary David Davis are meeting Mr Barnier on Monday ahead of the next round of negotiations getting under way.
Talks between officials this week will focus for the first time on the “transitional” period – of about 18 months to two years – which both sides want after Brexit on 29 March 2019.
Potential sticking points include citizens’ rights, with the UK insisting EU nationals arriving during this time should not have the same future rights as those who arrive before Brexit day.
As he set off for London, Mr Barnier said time was of the essence.
“There is so much work, so we have decided for this reason to accelerate all the contacts,” he said.
“We want to reach a deal, respecting the guidelines of the European Council, respecting the rules of the single market of the Union. So once again we have not a minute to lose.”
Asked about the UK’s apparent decision to discount any future customs union, he suggested this was not news to him.
“We have to respect the red lines of the British government but they have to respect the rules of the union.”
The UK’s future relationship with the EU’s single market and customs union has been a topic of debate among leading Brexiteers and some of those closest to the prime minister.
In a customs union the UK would have tariff-free trade within the EU, but would lose the ability to strike its own deals with other countries.
In a position paper published in August, the UK set out two potential options for future long-term customs operations.
A “partnership” arrangement would see the UK “align precisely” with the EU in terms of imports and exports, removing the need for any customs checks between the two.
The UK would continue to operate its own checks on goods coming from outside the EU – and safeguards would be needed to prevent goods entering the EU that had not complied with its rules.
An alternative scenario would involve the UK extending customs checks to EU arrivals but under a “highly streamlined arrangement” to minimise disruption at ports and airports.
This would seek to make the existing system of customs checks “even more efficient”, for example using number plate recognition technology at ports, which could be linked to customs declarations for what the vehicles are carrying, meaning the vehicles do not have to be manually stopped and checked.
Conservative MP Kwasi Kwarteng, who is an aide to Chancellor Philip Hammond, suggested the latest statement on the customs union was “perfectly consistent” with what No 10 had been saying all along, given that Mrs May had been “pretty clear” for more than a year that the UK would be leaving.
Pressed on how he squared this reality with Mr Hammond’s stated desire for the UK and EU to move “very modestly” apart in terms of trade, he told BBC Radio 4’s Today that “being modestly apart does not mean you have to be in a customs union”.
The government’s 10-strong Brexit cabinet sub-committee will meet on Wednesday and Thursday as UK officials prepare to brief their EU counterparts on their vision for post-Brexit relations on Friday.
Home Secretary Amber Rudd – who was a leading figure in the Remain campaign – said on Sunday that the committee was “more united” than many Brexiteers think.
Quizzed on what the model of future relations might look like, she said she was “not intimidated at all” by critics’ warnings about customs unions membership and believed Mrs May had an “open mind” on the issue.
Labour said it was “foolhardy” to rule out any kind of customs union with the UK’s largest trading partner.
“The government must put jobs and the economy first, not their own internal party wrangling,” a party spokesman said.