The Democratic Unionist Party leader Arlene Foster regards a no-deal Brexit as the “likeliest outcome”, according to a leaked email seen by the Observer newspaper.

The newspaper said Ms Foster told Ashley Fox, leader of Conservative Members of the European Parliament (MEPs), over a dinner last week of her disappointment at a meeting with Michel Barnier, the French official leading the European Union’s negotiating team.

“She described Barnier as being difficult and hostile in her meeting today,” the leaked email cited by the Observer said. “AF [Arlene Foster] said the DUP were ready for a no deal scenario, which she now believed was the likeliest one.”

The Observer said it was one of several emails it had seen that had been “leaked from the highest levels of government”.

Earlier on Saturday, Ms Foster warned the British government not to make “the same mistake” with Brexit that late British prime minister Margaret Thatcher did with the Anglo-Irish Agreement (AIA) and override unionist concerns.

Ms Foster’s DUP props up the Conservatives at Westminster through a confidence-and-supply agreement.

However, this agreement has come under threat in recent days as Ms Foster has warned she will voted against any deal she believes undermines the union.

She said Ms Thatcher had “deeply regretted” agreeing to the Irish government having a formal consultative role in the North.

However, the AIA is widely regarded as leading to the peace process.

Writing in the Belfast Telegraph on Saturday, Foster warned: “We do not want or need the regrets of another prime minister.

“We want her to stand by her principles and instincts rather than accepting a dodgy deal foisted on her by others.”

The DUP objects to a Brexit backstop which would see Northern Ireland treated differently to the rest of the UK.

It does not want the region remaining in the European Union’s single market while Scotland, England and Wales leave.

“I would not tolerate a trade barrier between England and Wales any more than I would tolerate on between Northern Ireland and Great Britain,” she said.

“The dangers to the union and our single market were clearly demonstrated by how quickly the SNP demanded the same for Scotland as was offered to Northern Ireland.”

Ms Foster accused the EU of lying over the backstop.

“EU spin on offer suggested Northern Ireland would have the best of both worlds,” she said. “That is lie. We would not.”

Ms Foster again warned that no deal is better than a “dodgy” Brexit deal.

“I full appreciate the dangers of ‘no deal’ but the dangers of a bad deal are worse,” she said.

British and EU negotiating teams are meeting over the weekend to try to agree text on the Northern Ireland backstop ahead of a summit in Brussels next week.

Britain’s Brexit secretary Dominic Raab has said any backstop must be time-limited, but Minister for Foreign Affairs Simon Coveney has said the backstop, which provides for there being no hard border on the island of Ireland, cannot be time-limited. – Additional reporting: Reuters