A battery responsible for triggering back-up electricity was “faulty” at the time Ipswich Hospital suffered a dip in power - causing a partial blackout for eight minutes, an investigation has found.

The blackout struck the hospital amid nationwide power outages on August 9, which affected huge swathes of the country.

While all 11 back-up generators at the hospital kicked in immediately, some departments were left without power for a short period of time - although the hospital has stressed no patients were at risk as a result.

Following an initial investigation, it has been revealed a faulty battery failed to switch the supply to one of the back-up generators at the time of the outage - so, while the emergency power source was working, it was not activated.

The issue only affected the main outpatients department, X-ray and pathology areas of the hospital, with the mains power restored by 5pm.

All of the affected areas were then hooked up to the back-up supply while precautionary tests were carried out from 5.30pm until 9.30pm.

The hospital said the battery was within its recommended life and would have been tested frequently.

A spokeswoman said: "Our initial investigation has shown that at 4.52pm on Friday, August 9, we lost our electricity supply until 5pm. We have 11 generators at Ipswich Hospital and all of them worked immediately.

"What we have found is that the battery which automatically operates one of the switch over systems from mains power to generator power was faulty despite being within its recommended life.

"We do test all of our electrical equipment and our generators frequently, in line with recommendations from NHS technical guidance. The problem was found very quickly.

"All of our estates staff worked hard and followed rigorous procedures to make sure all our patients and staff were kept safe.

"This issue only affected the main outpatients department, X-ray and pathology areas of the hospital. The generators were switched on in these areas by 5.30pm and then by 9.30pm we moved back to mains electricity once the faulty battery was replaced, and following rigorous safety checks and a period of mains stability monitoring."

Neill Moloney, managing director said: "All of our staff, including clinicians, managers and technical teams worked very hard to keep our patients safe and reassured. My thanks to everyone and indeed our patients and visitors for their support during this time".