Medical professionals have angrily accused Stormont's health boss Richard Pengelly of being "irresponsible" and putting patients at risk by ordering budget cuts of £70 million.
They also described as a "sham" public consultations aimed at deciding where the cuts should be made.
Around 200 representatives from medical bodies and trade unions staged a protest at Parliament Buildings on Tuesday against the health cuts.
In August, Northern Ireland's five health trusts unveiled plans to make £70 million of cuts to plug budget shortfalls.
The proposals, which were opened to public consultation, included a cut in agency or locum staff and a reduction of non-urgent elective surgery.
The Belfast Trust also proposed the closure of about 100 bed places while the Northern Trust suggested closing two wards in Whiteabbey Hospital.
Members of the NI Committee of the Irish congress of Trade Unions (NIC-ICTU), representing 11 health unions, marched through the grounds of Stormont to deliver a letter of protest to Permanent Secretary Richard Pengelly at the Department of Health in Castle Buildings.
The letter, signed by the chairwoman of the NIC-ICTU Health Policy Committee Anne Speed, expressed "profound concerns about the actions taken by (Mr Pengelly) and (his) department, which will, as publicly stated by clinicians, put patients and clients at risk and are causing widespread public concern".
The group said they are unaware of any attempts by the department to secure the funding shortfall either through negotiation with the Department of Finance, other departments or representations to the Secretary of State.
The letter continued: "You are taking these decisions at a time when additional funding has been announced for the Health Service in England.
"You are also aware that a further £1 billion has been agreed for the NI allocation as a result of the 'confidence and supply' agreement between the UK Government and the DUP."
The group claimed that the consultation by Trusts "is no more than a sham" as Trust Boards have been instructed to meet in mid-October to make final cuts decisions "despite the fact that the public consultation closes on October 5.
They have demanded that Mr Pengelly and the Department of Health stops the current process and engages with the Trade Union Movement, health unions, staff, service users and stake holders "to find a way through the current crisis which does not adversely impact on patients, clients and front line staff".
A Department of Health spokesperson said: “We’ve just received the letter today. It is an important contribution to the consultation process.”