Tánaiste Leo Varadkar has said he is "not going to get too concerned or too bothered" by new DUP leader Edwin Poots's criticism of him.
During a strongly-worded speech on Thursday night, Mr Poots said relationships with the Irish Government are "really, really bad" and claimed it would "starve" Northern Ireland of medicines and food.
He criticised the Northern Ireland Protocol and said Mr Varadkar and foreign affairs minister Simon Coveney had contributed to strained relationships during the Brexit negotiations.
Mr Varadkar yesterday congratulated Mr Poots on his election.
He said the Lagan Valley MLA was "somebody we've worked with in the past", adding that Mr Coveney worked very closely with Mr Poots on getting the Assembly restored in January last year.
The Tánaiste acknowledged there are "some practical differences with the Northern Ireland Protocol".
"When it comes to the Northern Ireland Protocol, I've never wanted any barriers to trade north or south, between Britain and Ireland, or between Northern Ireland and Great Britain," he said.
"The protocol was put in place because there had to be checks somewhere and we felt it was better to have those checks at one or two ports as opposed to locations where there is a land border and I stand over that decision to protect the country from a hard border."
Mr Poots said that he will engage with the Irish Government after he takes over from Ms Foster today.
He said on Thursday that while he respects Taoiseach Micheál Martin, he strongly criticised Mr Varadkar, Mr Coveney and the Northern Ireland Protocol.
He said they "took photographs of blown up border posts to impose upon Northern Ireland people a harshest form of customs, and an internal market that doesn’t exist anywhere else in the world" during the Brexit negotiations.
"They’re going to starve Northern Ireland people of medicines, no less, cancer drugs and other materials such as the food that’s on our table," he said.
"And I’d say that’s a shame on the Irish Government that they done that. And that belongs to Fine Gael under the leadership of Leo Varadkar and Simon Coveney. So relationships are really, really bad with the Irish Government as a consequence."