Taoiseach Leo Varadkar has told opposition leaders there is a “risk” border checks in a no-deal Brexit could be operated in France or the Netherlands as opposed to on the island of Ireland.

In a private meeting with party leaders yesterday evening, Mr Varadkar and his department secretary general John Callinan said the EU could move control of any needed border away from Ireland and onto the continent.

This was one of the risks in a no-deal, opposition leaders were told. Such a scenario would see Ireland and Britain treated as one block, a source at the meeting confirmed, and must be “avoided at all costs”.

Up until now, both Dublin and London have pledged that no new border would be erected. However, an EU spokesman yesterday said that in the event of a no-deal, a hard border would be needed.

Opposition leaders were told of this risk of a third country operating new border processes. This would be in the case were customs or goods checks were not trusted here and produce leaving Ireland for mainland Europe would instead be vetted at ports such as in Calais in France or Rotterdam in the Netherlands.

Mr Varadkar met Labour leader Brendan Howlin, Fianna Fáil leader Micheal Martin, Green leader Eamon Ryan, Independent TDs Mattie McGrath and Tommy Broughan, and Sinn Féin leader Mary Lou McDonald.

Relaying the points made by the Taoiseach and Mr Callinan, one source present said: “It was said that it would be very catastrophic for us if the border was in Calais. The whole vibe is to sit tight. There was a mention of this in extremis and for it be avoided at all costs.”

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

While it was a hypothetical situation raised by Mr Varadkar and his department head, the leaders were told this was one of the risks of a Brexit no-deal. The leaders and TDs were told this would involve a third country, such as France, taking the lead on a border infrastructure that would essentially apply to Ireland and the UK “as one block”.

This would see a border essentially put in place in Calais as opposed to Monaghan,” said one shocked TD.

Nonetheless, Mr Varadkar stressed to opposition TDs that he still thought there would be deal before Brexit.

Tánaiste Simon Coveney suggested there could be developments on a deal next week, while speaking in the Seanad last night. He told the Upper House that there would be more clarity next Tuesday evening, after British prime minister Theresa May brings her plan B options before MPs there.

A number of votes will take place, Mr Coveney said, and Ms May would respond after that.