THE PSNI had access to private information obtained by a top-secret computer program that snoops on phones, the internet and social media, it has been claimed.

A document leaked by US whistleblower Edward Snowden suggests that the PSNI could access an intelligence treasure trove operated by Britain's Government Communications Headquarters (GCHQ).

The secret surveillance unit is responsible for monitoring communications on behalf of the British government.

It has emerged the organisation used computer software known as Milkwhite Enrichment Service (MES) to harvest private information to be used by intelligence organisations.

Other agencies believed to have access include Revenue and Customs, the Scottish Recording Agency, and the Serious Organised Crime Agency (SOCA), which was later absorbed by the National Crime Agency.

It is believed Milkwhite has the capability to tap into social media, the internet and the phone records of private individuals.

While it was known that various intelligence agencies gather their own information, the leaked document suggests that data is widely shared.

The document, which was dated March 2011, reveals that the PSNI had access to information via an internet data unit then hosted by SOCA.

It is not known if the force must get permission from a judge before accessing information on individuals.

Professor Anthony Glees, who is director of the Centre for Security and Intelligence Studies at the University of Buckingham, said programmes like Milkwhite have algorithms that “allow them to pick up data of interest to security services”.

The intelligence expert said the existence of the programme “was not a revelation” to experts.

Details of the PSNI’s links to the MES system emerged after a US website posted documents leaked by Edward Snowden earlier this year.

A former computer expert and CIA employee, he leaked sensitive information belonging to America’s National Security Agency in 2013.

The disclosures have lifted the lid on surveillance programmes operated by governments across the globe.

The PSNI was asked if it uses MES or a similar programme to gather information.

It was also asked if the force accesses personal details without obtaining a warrant or other authority.

In response a spokesman said: “It would be inappropriate for policing to become involved in what is clearly a regulatory matter.

“I therefore suggest that your best course of action is to write to the Interception of Communications Commissioners Office who have oversight of such matters.”