The Belfast Health Trust tested only a sixth of patients who were discharged from hospitals to care homes for Covid-19 during the early weeks of the pandemic.
The trust has also admitted a number of those sent to care homes from hospitals had tested positive for the virus.
Some 318 patients were discharged to care homes between March 1 and April 15 this year. Of these, 52 were tested for Covid-19 prior to discharge.
Of those patients who were tested, the trust stated: "The majority of those tested were negative.
"Less than five tested positive and none were inconclusive." The trust failed to state exactly how many people tested positive before being sent to a care home.
Responding to a Freedom of Information (FoI) request, the trust explained: "It is important to note that during the time period of this FoI request, there was no requirement set out in the Department of Health's 'Interim Protocol for Testing of Covid-19' to test care home residents prior to discharge."
Updated guidelines on testing were issued in April.
Figures have shown consistently around half of deaths here occurred in care homes.
Last month the Northern Trust said about one in six of its 433 patients returned to care homes were tested in the same period. Six tested positive.
The South Eastern Trust tested one in five in this same period.
Out of these 34 patients, one had coronavirus and was sent to a "Covid specific recovery unit".
Both trusts said they were acting within the guidelines at the time.