The Mater Hospital has asked the public to avoid their emergency department where possible as the hospital is under "significant pressure".
The hospital said this is due to the combination of an increase in the number of Covid-19 patients, high numbers of people in the emergency department and staff being out of work for Covid-19 related reasons.
Bosses asked patients with non-emergency conditions "to seek assistance from other parts of the health service such as minor injury units or their GP".
They said those who come to the emergency department with non-emergency conditions "can expect long waits".
The Mater, in Phibsborough, said anyone who needs emergency care should still attend the hospital for care and they said patients in those situations should not delay seeking such treatment.
Those with appointments scheduled should attend as planned unless contacted by the hospital.
The Mater said it "apologises for any inconvenience this causes and thank the public for their understanding and cooperation".
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