Former Taoiseach Bertie Ahern has said it is essential Ireland keeps the coalition of EU member states behind it and not allow the British to "push and shove" into a future relationship without nailing down the arrangements on the border issue.
Mr Ahern said that it would be a disaster to allow the UK move to the future relationship and say is a withdrawal agreement until we have "absolute agreement on what happens on the 1st of January 2021."
Mr Ahern told Today with Sean O'Rourke on RTÉ Radio 1 that Ireland may need to make further concessions along the way, adding it is "not unreasonable" that at the point of delivery, for example on the factory floor, that there are proper regulatory checks.
He said as far as possible Ireland wants a seamless, friction-less border where Northern Ireland is still in the customs union with no obstacles to trade or travel.
Mr Ahern said he believed the UK wanted to remain in the single market although that is not its stated position.
He said that the UK may also need to make further concessions, but surmised that Theresa May was constrained from changing her position by the upcoming Tory party conference.