The Irish Prime Minister Leo Varadkar has reiterated that the border backstop "can’t have an expiry date".
However, during question time in the Irish Parliament he re-iterated that it was the Irish government’s intention that the backstop should never have to be invoked.
The Taoiseach acknowledged that it was a "difficult time" for unionists in Northern Ireland, and that they might feel "vulnerable".
But he said: "I want to say to them that the Good Friday Agreement will be protected, and that includes the fact that we respect the territorial integrity of the UK."
Sinn Fein’s Pearse Doherty told Irish MPs that the leaders of his party would be speaking on the phone with Theresa May after 17:00 GMT.