She said: “There was an understanding between myself and the then Taoiseach Enda Kenny to work together.
“Just before Enda left the new administration took over and things changed and those below the radar contacts ceased to happen. I regret that.”
She went on: “The focus of Leo Varadkar and his very muscular foreign minister Simon Coveney was not to get a Brexit done that recognised the issues in Northern Ireland as part of the UK but more as to how they could frustrate the outworkings of the democratic vote that had taken place in the UK, trying to stop Brexit.
“And if they couldn’t do that they tried to separate Northern Ireland out of the rest of the UK.”
She added: “I think that was a very foolish reckless thing to do actually. I hope relations can be rebuilt again.”
Giving a vote of thanks to a speech by Lord Frost, who negotiated the Brexit deal, she warned that Unionists are “not content with the arrangements that are there” with the Protocol.
She said: “Prime Minister [Theresa] May did make a number of early errors in relation to the negotiations with the European Union.
“She believed political aspirations as opposed to what was the reality of the situation in Northern Ireland and, indeed, the Belfast Agreement.”
Ms Frost said it was wrong to accept the EU premise to solve the border situation without knowing the trading arrangement.
“In other words provide an answer before you know what the question is, which was an incredible situation for the Government to get themselves into,” Ms Foster noted.
Lord Frost blamed Ms May’s Government for leaving Boris Johnson and him with a “daunting prospect”.
He said: “In considering how to proceed, we faced serious dilemmas and many factors that needed to be balanced. They explain why the final deal was imperfect.”
He also took a swipe at Remainers including former Speaker John Bercow who tried to tear up British constitutional norms to overturn the Brexit referendum result.
“First, we had to deal with the growing belief among the political class and the public that the referendum result simply couldn’t be delivered.
“Second, we faced the shredding of our constitutional norms, with Parliament effectively taking on the role of the executive for Brexit purposes, and hamstringing the Government’s ability to negotiate.
“Third, it was clear that a substantial proportion of the political class, in all parties, wanted to find a way of reversing the referendum result – which would have had, in our view, a devastating impact on faith in democracy itself.”