Admissions to a Co Antrim nursing home - whose owners received a glowing public recommendation from the First Minister - have been suspended.
It comes after an unannounced inspection revealed a raft of concerns over the level of patient care and management of staff and medicines.
An investigation by Patients First NI uncovered a number of incidents over the last four years where 'failure to comply' notices had been issued by the regulatory body RQIA in respect of concerns at Rose Martha Court in Ballymena.
The most recent relates to an inspection on October 13.
In the first of two notices issued by the RQIA following that inspection, "serious concerns" were identified in relation to the quality of care, as well as a "lack of evidence that safe and effective care and treatment was being delivered to patients consistently".
Other concerns included:
Under the terms and conditions of the enforcement action issued by the RQIA, the management of Rose Martha Court have been given until later this month to redress the requirements set out by the regulatory body.
A spokeswoman for the Northern Trust said Rose Martha Court was a privately-owned home and not under its management.
She said that, following the inspection and after a meeting with owners Runwood Homes, admissions to the facility had been suspended.
Runwood Homes said it was "deeply disappointed" the inspection on October 13 found the home did not meet the high standards it expected.
Runwood Homes added: "We have invested a considerable amount of resources and training within the care home to achieve a high standard and this will continue.
"We are working in collaboration with key stakeholders to ensure that all issues identified during this inspection are resolved, with an emphasis on developing a model of best practice."
In August Runwood Homes announced that it was expanding its operations in Northern Ireland.
At the time First Minister Arlene Foster said the "major investment in our local private care sector by Runwood Homes reflects the desire of the group to provide a model of best practice for older people in the community".