Antrim Area Hospital is "operating beyond capacity" with 27 sick patients awaiting admission, the Northern Trust has warned.
Patients were on Monday evening asked not to attend the hospital's emergency department unless urgent medical care was requited.
The warning came as the Trust warned Northern Ireland is "in the midst of the second Covid surge" with the hospital taking care of very ill patients.
Meanwhile, the Northern Ireland Ambulance Service (NIAS) said it was "extremely busy" on Monday evening and asked for patience.
"We will prioritise calls to provide the quickest response to the most seriously ill or injured," it said.
Earlier on Monday, five further deaths were confirmed as a result of Covid-19.
All five deaths occurred within the past 24 hours and brings the death toll from the virus in the region to 658.
Three of the deaths occurred in hospital in the Belfast council area. One man aged between 60-79, one man aged 80 and over and one woman aged 80 and over have sadly passed away.
The other deaths were a woman aged 80 and over in hospital in the Derry City and Strabane council area and a woman aged between 40 and 59 in hospital in Ards and North Down.
A further 727 cases of Covid-19 have also been confirmed since Sunday after 4,893 tests were carried out on 2,866 people.
In total 34,832 people have tested positive for the virus in Northern Ireland since the pandemic began.
Over the past seven days 6,828 people have tested positive for the virus, with 1,714 in the Belfast council area and 810 in Derry City and Strabane.
There are currently 342 Covid-19 inpatients in Northern Ireland's hospitals, with 39 in intensive care units.
Hospital bed occupancy currently stands at 96%, with 9 intensive care unit beds remaining free.
In Northern Ireland's care homes there are currently 99 active Covid-19 outbreaks.
It comes after it was revealed police in Northern Ireland have fined 45 people since March for failure to self-isolate.
All 45 were fined £1,000 for their failure to comply with coronavirus regulations.
Meanwhile, 400 prohibition notices were issued, with 81 to commercial premises for not following the coronavirus regulations and 319 to private dwellings.
In total 1598 penalty notices were issued to over 18s for breaking the rules in place to stop the spread of the virus, while 1075 community resolution notices were handed out.
A total of 3,118 enforcement actions have been taken by police since the pandemic began in March.
Read Monday's blog below: