Five patients in the intensive care unit of a Dublin children's hospital were transferred to another hospital in the city following a power outage in the early hours of this morning.

Temple Street Children's University Hospital said there was an eight-second interruption to its power supply at 3am and the hospital switched to generator power.

An investigation into the issue revealed a fault with the transformer in the hospital's sub-station, which will have to be replaced.

In a statement, the hospital said five patients in the Paediatric Intensive Care Unit were transferred to Our Lady's Children's Hospital Crumlin.

Clinical Director Dr Adrienne Foran said that although the hospital was without power for just eight seconds, when it was realised that the transformer would have to be replaced, the "cautious decision" was made to move the five patients.

She said this was a purely precautionary move in case the generator failed and the patients were moved in a "nice, planned, elective way".

Other patients remained at the hospital and outpatient clinics ran this morning as planned.

However, the hospital postponed 20 scheduled surgeries and all elective x-rays. Parents were also urged not to bring their children to the hospital.

In a statement this evening, Temple Street hospital confirmed that the additional generator had arrived. 

The emergency department at the hospital were back on-call for ambulances from 6pm, and parents were also advised to bring their children to the emergency department as normal from this time.

The hospital said that the five patients from the Intensive Care Unit that were transferred to Our Lady's Children's Hospital Crumlin will be transferred back to Temple Street tomorrow morning. 

It said that all other normal services at the hospital, including planned elective surgeries, will resume from tomorrow morning. 

Earlier while speaking on RTÉ News at One, Dr Foran said the hospital had received superb support from colleagues in Crumlin and Tallaght and technical support and clinical back up, if needed, from the Mater and Beaumont hospitals.

She said they were very disappointed that surgeries had to be cancelled today and they had discussed going ahead with some of the more complex operations but felt it was not worth the risk.