The Mater Hospital is appealing to people to avoid its emergency department "where possible".
Hospital management says the Mater is under significant pressure due to a combination of a high volume of patients, an increased number of COVID-positive patients in the hospital, and staff who can't come to work due to contracting COVID or being a close contact.
Management at the facility is warning that people who turn up at the emergency department with non-emergency conditions can expect "long waits".
However, it's advising that anyone in need of emergency care will be treated - saying anyone who does need emergency treatment should not delay in seeking care.
Figures released by the HSE overnight showed the Mater had the most COVID-19 patients of any hospital in the country.
65 patients with the virus are being treated at the hospital - around 10% of the total number of patients with COVID currently in Irish hospitals.
INMO trolley figures, meanwhile, show 31 patients in the Mater's emergency department are waiting for a bed this morning.
