Staffing shortages have led to the temporary closure of 12 beds in two hospitals.
Six beds in the Downe Hospital and six in Lagan Valley are currently shut for inpatients.
Between five and eight beds have been closed daily at each hospital within the last two weeks as part of a plan spearheaded by the South Eastern Trust that is being reviewed daily. The reduction, it says, is to "allow nurse managers to staff their wards appropriately and safely".
But the move has led to angry calls for the Health and Social Care Board to step in and prevent further bed closures to stop what has been described as a "strategically managed decline in service".
Campaigners have also accused the trust of "chipping away at the current front line health services".
A drop in medical staff has been blamed on "staff sickness and maternity leave". A spokeswoman for the trust said the action was due to the implementation of a summer plan, and described it as a "normal operational decision".
A further breakdown of figures released by the trust yesterday revealed the Downe Hospital 'down-turned' – or temporarily closed – five beds at the end of June.
And on July 11 "due to the significant number of empty beds" it closed an additional three – making a total of eight.
Within the plan there is the potential to close between 5 and 12 beds on each site.
"This has been kept under review daily and we have never been in a position to downturn 12 beds on either site," the trust spokeswoman said.
In an earlier statement the trust said "severe shortages of staff due to staff sickness and maternity leave" were being blamed for the problems.
The A&E departments are open Monday to Friday from 8am to 8pm. The trust said the full number of beds should be reopened by September.
But SDLP MP Margaret Ritchie said both the Health Minister and the Health and Social Care Board needed to step in urgently.
"This decision has also been taken at a time of a public holiday when there has been an influx of visitors to the area – some of whom may need inpatient hospital services," she said.
Alliance councillor Patrick Clarke also called for action from the minister. He said: "I firmly believe that they are effectively closing the Downe Hospital by stealth following this bed reduction announcement, which makes me wonder whether they are actually fit for purpose."
There are 49 beds in Downe Hospital, Downpatrick. Forty of these are medical, nine for cardiology.
Currently six are closed. Lagan Valley Hospital, Lisburn, has 89 beds in total. Of these, 81 are medical, eight cardiology
Currently six beds are closed.