The health minister has been accused of "abdicating her responsibilities" after it emerged that emergency department waiting times across Northern Ireland have continued to increase.
Almost 900 patients were left waiting for treatment for more than 12 hours in December, Department of Health statistics show, more than triple the number in December 2015.
Ministerial targets say no patient attending an emergency care department should wait longer than 12 hours, but the Department of Health's latest statistics for the region show that in December 887 patients waited longer than 12 hours to be either treated and discharged or admitted.
The Department of Health said there had been a 5.7% increase in attendances last month. A total of 62,094 people attended emergency departments in December, an increase of 3,360 from the previous year.
The statistics also show that in December only 65.4% of patients were treated and discharged or admitted within four hours. The target is 95%.
Ulster Unionist Joanne Dobson hit out at Health Minister Michelle O'Neill and said she "should be ashamed of herself".
The Assembly election candidate said: "By presiding over a deepening crisis in our health service, she has effectively abdicated the responsibilities she had as health minister to patients.
"The crisis in our local health service is wholly unprecedented. Never before in the history of the NHS have so many people been waiting so long to receive a diagnosis or treatment.
"Every single aspect of the local health service is under pressure, from the provision of domiciliary care places right up to the outrageous delays that too many patients are experiencing in receiving treatment for life-threatening illnesses."
A comprehensive plan was due to be published by the health minister this month to tackle the waiting list crisis, but with no agreed budget and a collapsed Assembly no action has been taken.
Ms Dobson said: "The latest publication of hospital waiting times illustrates that the people who will continue to be most affected by the RHI scandal, and the subsequent failure to get our public finances in order, are tragically also those who need our public services - such as the NHS - the most."