Ambulance bosses are facing official sanctions after repeatedly failing to address the problem of filthy vehicles and blood splattered equipment over a seven-month period.
Bloodstains found by inspectors in one ambulance station were still there two months later, Northern Ireland's health watchdog found.
The news comes after the Regulation and Quality Improvement Authority (RQIA) carried out unannounced spot checks at 21 ambulance stations across the region in just one day last month.
The RQIA has been so concerned by conditions at ambulance stations and inside vehicles that it has asked the Department of Health to intervene.
It is the first time such action has ever been taken against a health trust and comes just days after a paramedic told the Belfast Telegraph that ambulances are normally only cleaned every six months due to staff pressures.
Issues about the state of Northern Ireland's ambulances - which transport some of the most vulnerable and sick patients - were first raised last July when the RQIA visited the NI Ambulance Service station at Broadway in west Belfast.
Patient equipment - including stretchers, suction machines and defibrillator - was visibly dirty, while a clinical waste bin was bloodstained.
An inspection of the ambulance station in Bangor two weeks later raised similar concerns, and the NI Ambulance Service was ordered to implement urgent measures to raise standards.
However, follow-up inspections two months later found insufficient action had been taken. It is understood inspectors found bloodstains that had been discovered during earlier visits remained on equipment they had previously examined.
The RQIA carried out a third inspection at Craigavon ambulance station on February 8 - and again concerns were raised about patient safety given serious concerns about lapses in hygiene standards.
An RQIA spokesman said it took further enforcement action.
As a direct result of the continued failure to meet basic safety standards, RQIA planned a major operation to visit 21 ambulance stations across Northern Ireland on February 22.
The RQIA spokesman continued: "A good standard of hygiene and cleanliness was evident in a number of stations and vehicles.
"However, RQIA found that a number of stations and vehicles were of an unacceptable standard with regard to infection prevention and control, hygiene and cleanliness.
"As a result of RQIA's findings on February 22, and evidence of limited progress to address issues previously identified at Bangor, Broadway and Craigavon ambulance stations and vehicles, on February 26, RQIA recommended that the Department of Health implement a special measure to support NIAS.
"We recommended the secondment into NIAS of a senior practitioner with experience in infection prevention and control, governance and assurance.
"This week, the Department of Health has accepted RQIA's recommendation, and has advised NIAS to proceed with this special measure."
A spokeswoman from the Department of Health said they are working closely with the NIAS to ensure they have the necessary support in place to address RQIA concerns as soon as possible.
An NIAS spokesman said the trust welcomes the offer of additional support which he said will "complement the range of measures we have already taken to address the immediate issues identified".
He continued: "NIAS takes this matter very seriously and are committed to take all the necessary steps to ensure our stations and vehicles meet the high standards required to protect the patients who use our services."