The Government believes only an "ultrasoft Brexit" can honour previous agreements struck between Dublin and the main Northern Ireland parties, including the Democratic Unionist Party, on how to handle Britain's withdrawal from the EU.
The position in Dublin is that either Northern Ireland on its own or Britain as a whole must stay in the European single market and customs union to avoid an economic or trade Border in Ireland.
Senior Government figures maintain that it is the responsibility of the British government and those in favour of Brexit, such as the DUP, to outline how a Border with the North can be avoided through technology or other means as an alternative to the "ultrasoft Brexit".
Sources are pointing to a set of principles agreed between the Dublin and the previous Northern Ireland executive in November at the North-South Ministerial Council.
Regular meetings
The body, set up as part of the Belfast Agreement in 1998, sees regular meetings between Ministers in Dublin and their colleagues in the Northern Ireland executive.
It agreed a set of four “joint principles” on Brexit which included a commitment to “protecting the free movement of people, goods, capital and services”.
The Government believes this can only be achieved by what senior sources are calling an “ultrasoft Brexit”, which would mean either Northern Ireland on its own – or the UK in its entirety – staying in the European single market and customs union.
There is currently no Northern Ireland Executive in place because of the ongoing political stalemate in Belfast following the Stormont elections in March.
Splitting Northern Ireland off from the rest of the UK and allowing it remain in the single market or customs union on its own would be strongly opposed by the DUP, which is propping up the Conservative government in London under a confidence and supply deal.
Intervention
The development follows Taoiseach Leo Varadkar’s intervention last week when he said Ireland was not “going to design a Border for the Brexiteers”.
Mr Varadkar’s statement led to an angry response from the DUP.
Government sources maintain, however, that Mr Varadkar was only restating the Dublin position and was not changing policy. It is understood he told British prime minister Theresa May in a meeting in Downing Street in June that the Government does not want an economic Border.
However, it is acknowledged that the tone of the comments of late are far more forceful than before, with the previous position expressed in a vaguer or subtler fashion.
Speaking on Monday, Mr Varadkar said Brexit was a “British policy, not an Irish one” but said it is part of his remit to “keep the door open” to the UK remaining in the EU, the single market and the customs union. He said the best way to achieve that is for the UK to “at least” stay in the single market and customs union.