LIAM Fox has upped the ante on Brexit, suggesting there could be no deal on the key issue of the Irish border until there was an “end state” on Britain’s future trading relationship with the European Union.

The International Trade Secretary’s intervention came after Phil Hogan, Ireland’s European Commissioner, made clear Dublin would “continue to play tough to the end” over its threat to veto trade talks until it had guarantees over the border.

And he stressed how it was a “very simple fact” that the UK deciding to stay inside the single market and customs union, or allowing Northern Ireland to do so, would end the stand-off.

But Dr Fox, a leading Brexiteer, hit back, saying: "We don't want there to be a hard border but the UK is going to be leaving the customs union and the single market."

He told Sky News's Sunday with Niall Paterson: "We have always had exceptions for Ireland - whether it's in our voting rights, our rights of residence in the UK, we have always accepted a certain asymmetry and that will have to be part of whatever agreement we come to with the European Union but we can't come to a final answer to the Irish question until we get an idea of the end state.

"And until we get into discussions with the EU on the end state that will be very difficult, so the quicker that we can do that the better and we are still in a position where the EU doesn't want to do that," said the Scot.

He was echoing Arlene Foster, the leader of the Democratic Unionist Party, who has made clear the Irish border issue is tied up not in the first phase of talks, currently going on, but in the second phase to do with trade.

She told her party conference on Saturday: "We will not support any arrangements that create barriers to trade between Northern Ireland and the rest of the United Kingdom or any suggestion that Northern Ireland, unlike the rest of the UK, will have to mirror European regulations."

The DUP, whose 10 MPs mean it is the largest Northern Irish party at Westminster, is maintaining the Tory majority in the Commons through a so-called “confidence and supply” arrangement.

On Tuesday, a vote in the Irish Parliament could lead to the collapse of the minority government of Taoiseach Leo Varadkar, which would disrupt the EU negotiations.

Speaking during a visit to New Zealand, Dr Fox blamed the European Commission's "obsession" with forging a closer union for the delays in the Brexit talks.

"The European Union countries need to consider the welfare and the economic prosperity of their people as opposed to the obsession of the commission about the concept of ever-closer union. This needs to be an economic Brexit not a political one."

But John McDonnell, the Shadow Chancellor, said he was “worried” by Dr Fox’s comments on the Irish border issue.

“The one thing that we don't want to do is jeopardise any movement quickly because we need movement to enable us to get into the proper trade negotiations. So I'm hoping that isn't a Downing Street sanctioned statement that's he's made,” he said.

Earlier, Mr McDonnell said it was important not to lose any of the gains from the peace process in Ireland during Brexit talks.

"So yes, we've said all the way along now that customs union, single market, all these options have got to be on the table now as part of the negotiations, and then through those negotiations see what security that people feel that we can give as a result of that," he told ITV’s Peston on Sunday.

Theresa May has been given until December 4 by Brussels to come up with further proposals on issues including the Irish border, the Brexit divorce bill and citizens' rights if European leaders are to give the green light to moving on to the next phase of negotiations covering the future relationship between the UK and Brussels. On that date, the Prime Minister is due to have another dinner with Jean-Claude Juncker, the European Commission President, which will take place just days before the crunch December European Council.

In an interview with The Observer, Mr Hogan, the EU's agriculture commissioner, took a swipe at the Government's approach to Brexit, saying: "I continue to be amazed at the blind faith that some in London place in theoretical future free trade agreements.

"First, the best possible FTA with the EU will fall far short of being in the single market. This fact is simply not understood in the UK.

"Most real costs to cross-border business today are not tariffs; they are about standards, about customs procedures, about red tape. These are solved in the single market but not in an FTA."

Ruth Davidson, put up to defend the UK Government on the BBC’s Andrew Marr Show, suggested a last-minute deal would be agreed and acknowledged it would be a setback if there was not progress at the December summit.

"The people that walk up to the microphones and speak to their home audience don't always reflect the negotiation and the progress that is going on in the room. When it comes to European negotiations it's always a five-past-midnight job," declared the Scottish Conservative leader.

Ms Davidson said that unless progress on to the next phase was made in December "we are rapidly going to run out of time" for a transitional deal to be put in place.

"I don't think it means that the world has ended but I do think it's a setback," she admitted.

Labour’s Barry Gardiner told the same programme Labour had not ruled out staying in the single market or a customs union with the EU post Brexit but insisted he could not say what his party would do as it was not at the negotiating table.

"It's not our call and it would be foolish of an Opposition to actually put out there and say this is the solution, when we're not in the negotiating table itself,” argued the Shadow International Trade Secretary.

"If we're at the negotiating table, we can have those discussions. I'd be very happy if Theresa May wanted to move over and call that election and let us do that.

"But until we're round that table, it's not sensible to say what you can get out of the negotiations, because you're not sitting there like you and I are, looking at the whites of each other's eyes and getting a deal," added the Scot.

Meanwhile it emerged the UK could be required to follow new rules implemented by the EU during a Brexit transition period.

The position set out by Michel Barnier, the EU’s chief negotiator, in leaked documents would make the application of new EU rules a condition of a transitional deal, meaning Britain could be subject to further Brussels' regulations for about two years after leaving the bloc.

Mrs May hopes to secure an implementation period between the UK's formal exit date and the commencement of any post-Brexit trade deal in order to give businesses time to adjust to the new arrangements, but accepting the imposition of new rules could trigger a revolt by Eurosceptics.

It would also go against the approach to an implementation period set out by the PM in her Florence speech, where she said the "framework for this strictly time-limited period...would be the existing structure of EU rules and regulations".

The Independent obtained a presentation drawn up by Mr Barnier for representatives of the EU27 in which he said a transitional deal would involve the "automatic application in the UK of new EU rules post-30 March 2019".

Foreign Secretary Boris Johnson has already indicated that accepting further regulations from Brussels would cross a red line.

Mrs May was also under pressure not to water down a red line on the European Court of Justice's jurisdiction ending when the UK left the EU.

The Sunday Telegraph reported that Eurosceptic ministers and backbenchers have expressed alarm at a plan being pushed in the Cabinet's Brexit sub-committee for the UK to agree to a system of "voluntary referral" of cases to the Luxembourg court.