THE situation in emergency departments is "dire" with one in seven patients facing delays of 12 hours or more last month.
The Royal College of Emergency Medicine NI said "patient care is now regularly being compromised, their safety is at risk".
Figures reveal that in last quarter, A&E departments witnessed the highest number of 12 hour waits on record.
In December alone, more than half of all patients were delayed by four hours or more and one in seven delayed by 12 hours or more.
In October 2021, there were 7,825 12-hour waits - a 61 per cent increase compared to the same month the previous year.
There were 7,080 12-hour waits in November, a rise of 70 per cent and in December 2021, there were 7,506 12-hour waits - a 45 per cent increase.
Other statistics show a rise in the number of people attending A&E departments with 56,031 attendances in October 2021 - a 31 per cent increase on the previous year.
In November, 52,300 people attended - a rise of 38 per cent and in December, there were 51,872 attendances, up 33 per cent.
Dr Paul Kerr, vice president of the Royal College of Emergency Medicine NI said the "situation in emergency departments in Northern Ireland is dire".
"The reality is that patient care is now regularly being compromised, their safety is at risk," he said.
"Dangerous crowding and unsafe corridor care are well and truly back, and these practices put all patients, but particularly our most vulnerable patients, at great risk.
"Four-hour performance in December sank again to a shockingly low 47.7 per cent, meaning over half of all patients attending an emergency department were waiting for four hours or more before being admitted, transferred or discharged.
"While the 12-hour data are shocking, in December more than one in seven patients were delayed by 12 hours or more in an emergency department before being admitted or discharged.
"We know that delays and long-waits in emergency departments are closely associated with patient harm and poor outcomes."
He added that urgent and emergency care continued to be in a deep crisis.
"While elective care is suffering too and rightly needs an action plan, it is vital that any plan includes actions to tackle both the elective care backlog as well as the crisis in unscheduled care," he added.
"The government must look at this data and recognise the harm that is coming to patients and take effective action in publishing an unscheduled care recovery plan."
