MICHELLE O'Neill has accused the British government of having a "reckless approach" towards Northern Ireland - after leaked documents revealed a hard border is inevitable in the event of a no-deal Brexit.
The Sinn Féin deputy leader also said she believed the government was dealing with the peace process "as though it's a commodity" and called on "those who value the progress of the past 21 years in Ireland" to oppose its stance.
She was reacting to papers leaked in The Sunday Times yesterday, which warn that the UK will be hit with a three-month "meltdown" at ports, with shortages of food, fuel and medicine if it leaves the EU without a deal on October 31.
The "Operation Yellowhammer" documents suggest that avoiding the return of a hard border in Ireland is likely to prove "unsustainable" and point to the probability of "direct action" and road blockades.
The classified papers state the no-deal would "severely disrupt trade" with the agri-food sector most severely hit, while significant jobs losses and a growth in black market goods are also anticipated.
Cabinet Minister Michael Gove tweeted yesterday that Operation Yellowhammer is a "worst case scenario".
Ms O'Neill said Ireland as a whole had been voicing concerns for months.
"These reports are no surprise to those of us on this side of the Irish Sea who have been voicing our very real concerns on the consequences of a no-deal Brexit for a considerable period of time directly with the British Government and the European Commission," she said.
"The island of Ireland faces its biggest and most profound challenges in a generation as the threat of a no-deal Brexit becomes a growing reality in the immediate time ahead."
"The consequences of a no-deal Brexit will result in a hard border which threatens our hard-won peace and undermines the political and economic progress of the past 21 years enjoyed across the whole island, but particularly in border communities which have been transformed.
"It will have devastating effects for the island of Ireland and our people, businesses, farmers, workers and communities," she said.
DUP leader Arlene Foster however said she believes the leaked dossier is "outdated".
"It comes from a time before Boris Johnson was prime minister, that's the first thing to say," Mrs Foster told BBC News NI.
"Secondly, it's been leaked with the idea really to undermine the prime minister before he goes out to Europe and meets European leaders this week."
SDLP leader Colum Eastwood said Mr Johnson does not understand the "complexities and fragilities of relationships in Ireland".
"The details in this leaked document now confirm that he doesn't care either," he said.
"We know that a no-deal Brexit will result in food and medicine shortages. Now, by the British Government's own admission, we know that trade across the border will grind to a halt.
"This British Government, far from sending a clear message to Brussels, is sending a clear message to people and businesses in Northern Ireland - they are willing to sacrifice our economic, political and social wellbeing to please rabid nativists in their own ranks.
"This British Government has no mandate for a no-deal Brexit. If they refuse to reverse position then they should call a general election and put it to the people."
Fianna Fáil Brexit spokeswoman, Lisa Chambers TD said the leaked paper "merely backs up all of the warnings" of the fallout from a no-deal Brexit, which she said would be catastrophic for the island.
"Reports of food, fuel and medicine shortages in Britain will surely result in some form of contagion in Ireland because of our extensive use of the UK land bridge," she said.
"There needs to be a greater sense of urgency from the government as well as more transparency about our level of preparedness for all Brexit eventualities. The October deadline is drawing closer but there is a real absence of information about where we are in terms of readiness for a no-deal outcome".
