British spies illegally kept intercepted people’s data for almost five years, a court said on Monday in a ruling that blamed the MI5 intelligence agency and the Home Office for “widespread corporate failure”, Reuters reported.

The investigative powers tribunal, which did not mention specific cases or intelligence targets in its written judgment, said there were “serious breaches” by MI5 between late 2014 and April 2019.

The UK Home Office has approved mass surveillance warrants

Judge Andrew Edis also said the Home Office had failed to make “adequate enquiries” when approving the mass surveillance warrants from 2016 to April 2019.

Human rights groups Liberty and Privacy International, which filed the complaint, said the decision showed MI5 had been breaking rules for years that had been “missed” by the Home Office.

The case concerned data obtained “in bulk” under the Investigatory Powers Act and prior legislation governing the interception of data for national security purposes.

Britain has been at the forefront of the battle between privacy and security since whistleblower Edward Snowden revealed details of mass surveillance tactics used by US and British agencies in 2013.

The Investigatory Powers Act provides vital tools to protect the public from criminals and terrorism, government and security officials say. But critics say it gives police and spies some of the widest spying capabilities in the West.

On Monday, Home Secretary Suella Braverman said the decision was due to “widespread corporate failures between the Home Office and MI5” which were “historic”.

In a written statement to parliament, she added that the tribunal had decided that it was “not that MI5 should not have had the material at all, just that a small part of it was retained for too long”.

The tribunal refused to quash any warrants that may have been issued illegally, or order MI5 to delete any data held illegally because “this would cause significant harm to national security”.