Ambulances may not always be sent out in response to emergency 999 calls in the current "exceptional circumstances", the service has said.
The Northern Ireland Ambulance Service (NIAS) has launched a new set of rules to help frontline staff deal with the growing impact of the coronavirus crisis.
As demand on the NHS continues to soar, the Northern Ireland Ambulance Service is implementing a level of escalation, including a specific Covid-19 protocol to categorise 999 calls. The new system allows for more specific questioning of patients to assess the likelihood of coronavirus symptoms so crews can be pre-warned about the need to use appropriate PPE.
It will also enable improved diagnosis of the severity of Covid-19 symptoms, meaning more specific advice will be given to individuals.
With demand on ambulance services growing, the new system will also allow NIAS to make sure every patient with immediately life-threatening and serious conditions - whether they are related to the outbreak or not - are appropriately prioritised for response.
NIAS warned it may be necessary to withhold an ambulance response to calls and deal with some through triage. These will be calls assessed as less serious than others, which do not need an ambulance response.
"NIAS apologises to any patients who may find themselves in this situation but we would ask for your understanding in advance," a statement said.
"These are exceptional circumstances requiring exceptional measures. NIAS will continue to monitor and review our response capacity and will react to any improvement in the situation without delay."
It added: "Until then, we would ask you to stay safe by following the measures identified to reduce the spread of the virus - stay home, keep socially distant and, regularly, wash your hands. We would particularly ask that the public consider the safety of our staff and reduce the risk of infection to them, and their families, by only calling 999 in real emergencies."