Organised criminals who carried out a cyberattack against Hackney Council months ago have now published some of the stolen personal data on the dark web and damaged backups to hinder recovery.

Experts supporting the council do not think the information - which is thought to be a "limited set of data" - has been published on a widely available public forum, or that it is accessible through internet search engines - but they are not 100 per cent sure.

The dark web is part of the internet that is not visible to search engines and requires specific software, configurations or authorisation to access it.

Hackney Council is working closely with the National Cyber Security Centre, the National Crime Agency, the Information Commissioner’s Office, the Met and other experts to investigate exactly what has been published.

According to the council, the vast majority of sensitive or personal information held by the council is unaffected. However, the data is being reviewed carefully and the council has pledged to support anybody directly affected.

It is still unable to share details about the nature of October's attack, which has left many council services experiencing continued disruption.

A spokesperson told the Gazette: "We appreciate that residents are very concerned about the impacts of the attack, but as this is a live criminal investigation, we are not able to provide further details."

In October, the council insisted all data that was wiped or stolen in the cyberattack was backed up, but this week, a spokesperson said: "We operate backups of our systems, but the attackers have been able to damage those backups, which means that the process of restoring systems is significantly more complex than our normal recovery plans.

"We moved quickly to introduce alternative systems where possible to deliver core services such as payments to residents receiving benefits and suppliers, and reporting of housing repairs.

"We are continuing to commit significant efforts to restoring and sustaining our services and we share residents’ anger and frustration at the impact that this criminal attack has had on the services they rely on."

In a statement, Hackney Mayor Phil Glanville said: "It is utterly deplorable that organised criminals chose last year to deliberately attack Hackney, damaging services and stealing from our borough, our staff and our residents in this way, and all while we were in the middle of responding to a global pandemic.

"Now four months on, at the start of a new year and as we are all responding to the second wave, they have decided to compound that attack and now release stolen data. Working with our partners, we will do everything we can to help bring them to justice."

He continued: "I fully understand and share the concern of residents and staff about any risk to their personal data, and we are working as quickly as possible with our partners to assess the data and take action, including informing people who are affected.

"While we believe this publication will not directly affect the vast majority of Hackney’s residents and businesses, that can feel like cold comfort, and we are sorry for the worry and upset this will cause them,

"We are already working closely with the police and other partners to assess any immediate actions we need to take, and will share further information about the additional action we will be taking as soon as we can."