An inspection of Owen Mor on the Culmore Road highlighted issues in May.
The home was closed to new admissions but later opened to patients despite inspectors’ concerns, the Regulation and Quality Improvement Authority (RQIA) said.
The Western Trust said “no residents have been placed at increased risk.”
In May, inspectors highlighted concerns about staff knowledge, including nurses not following policies and procedures, as well as inadequate records about areas of patient safety, such as falls, feeding and nutrition. at the 81-place facility.
The Trust has now confirmed that “46 short break residents and two temporary residents were admitted” to the care home after that inspection and prior to inspectors approving their requested improvements.
“No residents have been placed at increased risk,” the Trust said in a statement to BBC Radio Foyle.
“The Trust has confidence in the enhanced monitoring process that is in place, which is ensuring a clear focus on managing individual risks and the delivery of safe and effective care for every resident.”
After a follow up inspection last week, the regulator has now formally stopped new patient admissions.
It is the first time in Northern Ireland the regulator has issued such a notice.
On Tuesday RQIA chief executive Olive MacLeod said inspectors did not find the improvement that was expected, specifically at one unit during the follow up inspections.
The Western Trust said it informed the RQIA of the home’s phased reopening.
Earlier this week the home’s owners said they were working with an independent consultant to put in place a plan to address concerns.
The facility is for people with learning difficulties, mental health issues and dementia.