Ireland could be isolated with Britain in a worst-case no-deal Brexit, with a customs hard border erected in Calais or Rotterdam instead of along the Irish border.

Taoiseach Leo Varadkar told opposition party leaders of the “risk” that border checks could be operated in France or the Netherlands just hours after the European Commission warned a hard border is the “obvious” consequence of a no-deal Brexit.

In a private meeting with party leaders last night, Mr Varadkar and his department secretary general John Callinan said unless the Irish question is resolved, the EU could hypothetically move control of any border away from Ireland and onto the continent.

Such a scenario would remove the need for a hard border between the Republic and the North.

However, it would also mean Ireland and the UK would be treated as one bloc, several sources at the meeting told the Irish Examiner, which must be “avoided at all costs”.

Mr Callinan said technical EU rules could apply which require it to protect its outer reaches.

One source said: “The risk is restrictions could be imposed in Calais or Rotterdam as they [EU] would not trust us. It would be if the UK was bringing in chlorinated chicken or the likes into Ireland.”

A spokesperson for Mr Varadkar declined to comment last night, saying it was a “private meeting”.

Mr Varadkar and Mr Callinan raised the risk of a no-deal Brexit as the European Commission, for the first time, publicly warned that a hard border is an “obvious” consequence of Britain crashing out of the EU without a deal.

The commission’s chief spokesman, Margaritis Schinas, said a no-deal Brexit will inevitably cause a hard border in Ireland.

Just hours after British prime minister Theresa May refused to rule out the doomsday Brexit scenario, Mr Schinas was asked if a hard border can be avoided if there is no deal.

He said: “If you’d like me to push and speculate on what might happen in a no-deal scenario in Ireland, I think it is pretty obvious, you will have a hard border.

The remark led to alarm bells in Dublin amid growing fears a no-deal Brexit is becoming inevitable.

The Taoiseach’s spokesperson and Tánaiste Simon Coveney claimed such a scenario can still be avoided by the withdrawal treaty — despite last week’s landslide House of Commons vote against the plan.

Speaking at the weekly Cabinet briefing, Mr Varadkar’s spokesperson said “the Government is not in denial” over the scale of the crisis.

However, he repeatedly declined to explain how to avoid a no-deal Brexit without using the withdrawal agreement or the backstop, stressed “there are no preparations for a hard border”, and said it remains up to Britain to find a solution.

Asked if there has been any contact with the commission since Mr Schinas’s comments, the Taoiseach’s spokesperson added: “I’m not aware of any communication. No, we weren’t notified.”

At a separate briefing at Government Buildings, Mr Coveney repeatedly referred to the withdrawal agreement and backstop as “the solution” to the stand-off, saying “that is how we prevent this issue becoming a real problem”.