Thousands of NHS jobs will be lost in Northern Ireland and hospital units could close if the health service's budget is slashed by the Stormont Executive, Michael McGimpsey has warned.
The Health Minister said the future of the Ulster Hospital in Dundonald would be in doubt if £130 million was not made available for a new acute services unit.
Mr McGimpsey also threatened not to sign up to the Executive's final budget settlement if it did not adequately protect his department's funding.
"The Health Service currently in Northern Ireland is seriously underfunded," he said after Assembly question time.
"Any further reduction in the level of funding required fills me with dread.
"When I look forward into the future I see potentially large numbers of redundancies, I see potentially closures as well.
"We do not appear in this house to be prepared to fund a health service that we understand as being the British National Health Service."
When pressed on the potential scale of jobs losses, the minister said: "I am not talking hundreds, I'm talking thousands and I'm not scaremongering and I am very, very careful about what I say because our staff are so loyal to the Health Service that they deserve my loyalty back and the support of this house."
Mr McGimpsey's stark warning comes as executive ministers continue to work towards agreeing a draft budget to accommodate the £4 billion cut to the region's block grant over the next four years that was announced in the Chancellor's spending review last month.
Ministers intend to hammer out a provisional budget by November 16 - that will go before the Assembly and then out for public consultation before a final spending plan is decided upon some time in February.