The EU has set Britain a test it “cannot meet” with its demands to see a replacement for the Irish backstop, the Brexit secretary has said.

Stephen Barclay said the UK should be given another year to find a new policy for the Northern Ireland border.

The intervention comes as Downing Street said it would not be bound by an “artificial deadline” in talks.

“We are told the UK must provide legally operative text by the 31 October,” the cabinet minister Mr Barclay said in a speech in Madrid on Thursday.

“Yet the alternative to the backstop is not necessary until the end of the implementation period in December 2020.

“And this will be shaped by the future relationship – which is still to be determined.

Supreme Court protests: Boris Johnson's prorogation legal or not? Show all 15 1 /15 Supreme Court protests: Boris Johnson's prorogation legal or not? Supreme Court protests: Boris Johnson's prorogation legal or not? Protesters gather outside The Supreme Court ahead of a hearing on the legality of Boris Johnson's proroguing of Parliament Getty Supreme Court protests: Boris Johnson's prorogation legal or not? The supreme court justices will sit as a panel of 11 judges to hear the challenge, brought by campaigner Gina Miller, that the Prime Minister acted unlawfully when he advised the Queen to suspend parliament AP Supreme Court protests: Boris Johnson's prorogation legal or not? A woman protests outside the Supreme Court Reuters Supreme Court protests: Boris Johnson's prorogation legal or not? The PM sent lawmakers home on 9 September until 14 October, just over two weeks before the UK is due to leave the European Union AP Supreme Court protests: Boris Johnson's prorogation legal or not? Gina Miller arriving AP Supreme Court protests: Boris Johnson's prorogation legal or not? People protest outside the Supreme Court Reuters Supreme Court protests: Boris Johnson's prorogation legal or not? Boris Johnson likened himself to the Incredible Hulk days previous as he promised to ignore the Commons legislation ordering him to delay Brexit if negotiations break down PA Supreme Court protests: Boris Johnson's prorogation legal or not? Officials bring in documents Reuters Supreme Court protests: Boris Johnson's prorogation legal or not? Protesters hold banners outside the Supreme Court in London, Tuesday Sept. 17, 2019. The Supreme Court is set to decide whether Prime Minister Boris Johnson broke the law when he suspended Parliament on Sept. 9, sending lawmakers home until Oct. 14 â€” just over two weeks before the U.K. is due to leave the European Union. (AP Photo/Matt Dunham) Matt Dunham AP Supreme Court protests: Boris Johnson's prorogation legal or not? Protesters hold banners outside the Supreme Court in London, Tuesday Sept. 17, 2019. The Supreme Court is set to decide whether Prime Minister Boris Johnson broke the law when he suspended Parliament on Sept. 9, sending lawmakers home until Oct. 14 â€” just over two weeks before the U.K. is due to leave the European Union. (AP Photo/Matt Dunham) Matt Dunham AP Supreme Court protests: Boris Johnson's prorogation legal or not? Protesters hold banners outside the Supreme Court in London, Tuesday Sept. 17, 2019. The Supreme Court is set to decide whether Prime Minister Boris Johnson broke the law when he suspended Parliament on Sept. 9, sending lawmakers home until Oct. 14 â€” just over two weeks before the U.K. is due to leave the European Union. (AP Photo/Matt Dunham) Matt Dunham AP Supreme Court protests: Boris Johnson's prorogation legal or not? People protest outside the Supreme Court of the United Kingdom during a hearing on Prime Minister Boris Johnson's decision to prorogue parliament, in London, Britain September 17, 2019. REUTERS/Phil Noble PHIL NOBLE Reuters Supreme Court protests: Boris Johnson's prorogation legal or not? Protesters hold banners outside the Supreme Court in London, Tuesday Sept. 17, 2019. The Supreme Court is set to decide whether Prime Minister Boris Johnson broke the law when he suspended Parliament on Sept. 9, sending lawmakers home until Oct. 14 â€” just over two weeks before the U.K. is due to leave the European Union. (AP Photo/Matt Dunham) Matt Dunham AP Supreme Court protests: Boris Johnson's prorogation legal or not? Joanna Cherry of the Scottish National Party leaves the Supreme Court Reuters Supreme Court protests: Boris Johnson's prorogation legal or not? Demonstrators protest outside the Supreme court in central London on the first day of the hearing into the decision by the government to prorogue parliament on September 17, 2019. (Photo by Tolga Akmen / AFP)TOLGA AKMEN/AFP/Getty Images TOLGA AKMEN AFP/Getty

“In short why risk crystallising an undesirable result this November, when both sides can work together – until December 2020.

“In summary, the EU risks continuing to insist on a test that the UK cannot meet and that the UK parliament has rejected three times.”

The plea for more time was made after Emmanuel Macron and the Finnish presidency of the EU issued an ultimatum in Paris on Wednesday, giving Boris Johnson until the end of September to table workable proposals – or “it’s over”.

The UK is yet to meet EU requests to propose a concrete alternative to the Irish backstop, which Mr Johnson says must be scrapped. EU officials fear they may be “led up the garden path” by British negotiators, who had been visiting the EU capital frequently for talks, but with little sign of actual progress.

The admission is an about-face by the British government. Speaking alongside Angela Merkel in Berlin last month, Mr Johnson said he was “more than happy” with the “blistering timetable” of finding a replacement for the backstop within 30 days.

A European Commission spokesperson on Thursday afternoon confirmed the UK had sent “some documents” to Brussels ahead of a visit by Mr Barclay to meeting with Michel Barnier, the bloc’s chief negotiator, on Friday.

But a UK government spokesperson confirmed that the papers were not a concrete written proposal, telling reporters: “We have been having detailed discussions with the Commission’s taskforce 50 [negotiating team] in recent weeks. We have now shared in written form a series of confidential technical non-papers which reflect the ideas the UK has been putting forward.

“We will table formal written solutions when we are ready, not according to an artificial deadline, and when the EU is clear that it will engage constructively on them as a replacement to the backstop.”

The December 2020 date named by Mr Barclay is the end of the transition period negotiated by Theresa May. The EU has consistently said that if the withdrawal agreement is not approved, there cannot be a transition period – and that without a Northern Ireland backstop, there cannot be a withdrawal agreement.

Britain’s secretary of state for exiting the European Union Stephen Barclay (AFP/Getty) (AFP/Getty Images)

Mr Barclay’s latest statement is essentially a request for the EU to drop any demand for a backstop in the withdrawal agreement, and let the UK have a transition period without a backstop in place.

The transition period can be extended by another two years beyond December 2020 with the agreement of both the EU and UK, though the prime minister said earlier this week he had no “intention” to do so.

A European Commission spokesperson told reporters in Brussels on Thursday: “What I can confirm is that we have received documents from the UK. On this basis we will have technical discussions today and tomorrow on some aspects of customs, manufactured goods, and sanitary and phytosanitary rules.