It is understood that the same incident which hit the borough on Monday.

An investigation is continuing with the National Crime Agency and National Cyber Security Centre.

RBKC says it won’t be releasing details of the cause of the attack at this time.

A Kensington and Chelsea Council spokesperson said:

“Our IT teams have worked through the night this week and have now established the cause of a cyber incident which was identified on Monday 24 November. We will not be giving out further details of the incident at this stage because the investigation is continuing with the National Crime Agency and National Cyber Security Centre to establish exactly how our systems have been impacted and protect them from any further impacts. A number of successful mitigations are already in place.

“Some systems, including phone lines, are disrupted. If you need to contact Kensington and Chelsea Council, please use the phone numbers at the top of www.rbkc.gov.uk/contact-us/call-or-email-us. We’ve activated business continuity and emergency plans to ensure we are still delivering critical services to residents, focusing on supporting the most vulnerable.

“Our website is undergoing planned maintenance relating to ongoing management of the incident, so some pages may be in and out across the day and residents may not be able to use our online forms. We are working hard to bring services back online.

“We would like to apologise for any disruption and thank residents for their patience as we work to bring systems back online safely.

Cllr Elizabeth Campbell, leader of the Royal Borough of Kensington and Chelsea, said: 

“As soon as I was informed there might be a data break impacting residents, I asked officers to make sure we tell people at the earliest possible opportunity.

“Even if we do not yet have the full picture of what data has been copied, and whether that does include any personal details, it is the right thing to do.

“All I know is – as a resident myself – I would want to know this information as soon as possible and then be able to make my own choices, follow advice, and protect myself if I think necessary.”