SINN Féin has accused the British Government of showing a "blatant disregard" for Brexit's impact on Ireland and the Good Friday Agreement.
On Wednesday, former Brexit secretary David Davis admitted Downing Street had a "blind spot" when it came to Brexit and Ireland, saying more should have been done to resolve problems such as the Irish border.
But speaking on BBC Radio Ulster's Good Morning Ulster show today, Sinn Féin leader Mary Lou McDonald dismissed Mr Davis' claim and said it was more a case "active hostility" than blissful ignorance.
Her comments come as Theresa May attempts to resolve a crisis which saw the PM narrowly survive a vote of no confidence in her government tabled by Labour leader Jeremy Corbyn yesterday.
Mrs May survived by just 19 votes, 325 to 306, a day after the House of Commons overwhelmingly rejected her EU withdrawal deal in a record defeat.
"The hostility has been absolutely manifest for some time now," Mrs McDonald said this morning.
"I would regard the Boris Johnson, Jacob Rees-Mogg view of the world to be utterly, not blind to Irish interests, but actively hostile to them.
"I don't think this is a case of blissful ignorance on the part of strong elements of the British establishment, I think this is the policy of 'Britannia rules the waves'... a harking back to an imperial past".
The nationalist leader added that the British state "has more than a blind spot" when it comes to Ireland.
"They have a blatant disregard for the international obligations under that international agreement [the Good Friday Agreement]," she said.
Mr Davis, 70, had told fellow MPs at the European Scrutiny Committee on Wednesday that the lack of a functioning executive in Northern Ireland since January 2017 and the election of Taoiseach Leo Varadkar in June 2017 had left his former department "unpredictably handicapped".
He admitted that with hindsight he now believed the UK Government should have put "more resources" into solving issues that arose across the Irish Sea following the Brexit vote in June 2016.
"The original Taoiseach [Enda Kenny] took a slightly more constructive approach than came later... the attitude of the Irish authorities in the first year was different than what came later," Davis said.
Former Brexit Secretary David Davis has told a Westminster committee that the government has had a "blind spot" when it comes to Brexit and Ireland. He cites lack of NI executive, and change at top of Irish govt. With hindsight says he'd have put more resources into this issue... pic.twitter.com/vBvTTEv6PH
— Jayne McCormack (@BBCJayneMcC) 16 January 2019
"It might be a coincidence that it changed at the time Mr Varadkar came in, or it might have been his drive.
"Either way, it changed and we probably didn't react quickly enough".
The Tory politician, who resigned as Brexit secretary last July over Theresa May's EU withdrawal plan, further divulged that he had not initially viewed the lack of an executive at Stormont as a significant problem for the Brexit process.
He added: "Without the Northern Ireland executive sitting on the joint ministerial committee... there was a blind spot there."