No deal can be secured on the Irish border after Brexit until trade negotiations are settled with the EU, Liam Fox has said.

The International Trade Secretary raised further uncertainty over Northern Ireland as rows over a potential hard border threaten to derail Brexit talks.

Ireland’s EU Commissioner Phil Hogan was the latest voice from Dublin to call for the UK to remain in the customs union and single market – or allow Northern Ireland to do so – as the Republic has threatened to veto moves to trade negotiations without further reassurances there will not be a hard border.

However the Prime Minister’s DUP allies, who are keeping her in Downing Street after she lost her parliamentary majority, have vowed they will not tolerate any attempts to keep Northern Ireland within the EU trade agreements.

Dr Fox told Sky News’s Paterson on Sunday the final decision on the border could not be made until a UK-EU trade deal had been agreed – despite warnings from Brussels that trade talks cannot proceed until the border issue is settled.

He said: “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.

“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.

“We can’t get a final answer to the Irish question until we get an idea of the end state.

“And until we get into discussions with the European Union on the end state, that will be very difficult so the quicker we can do that the better – and we are still in the position where the EU doesn’t want to do that.”

He maintained the Government position that the UK would leave the customs union and the single market but insisted there would be no hard border – which would be traditionally required if Northern Ireland had different customs arrangements to its neighbours south of the border.

The ardent Brexiteer blamed Brussels for deadlocked talks, hitting out at the European Commission’s “obsession” with forging a closer union.

Dr Fox added: “I think 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.

“I think this needs to be an economic Brexit, not a political one.”

Shadow Chancellor John McDonnell reacted with concern to the comments, saying: “I’m worried about this news from Liam Fox this morning.

“I think 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.”

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Earlier, Shadow International Trade Secretary Barry Gardiner said that Labour had not ruled out staying in the single market or a customs union with the European Union after Brexit.

He told BBC One’s Andrew Marr Show: “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.

“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.”

The Prime Minister is under pressure to get EU leaders to approve her withdrawal offer at a crunch meeting of the European Council on 4 December, where she will need to address the key issues of citizens rights, the Irish border and the so-called “divorce bill”.

If she is successful then talks will shift to the future trade relationship and settling the transition, likely to be between 2019 and 2021.