How is MI5 different to MI6, what do they stand for and what do the spy agencies do?
Both agencies, dating back to the World War One, are tasked with protecting the country but their remits differ
THE agencies widely associated with fictional super spy James Bond both serve the same purpose - gathering intelligence.
But the secretive and highly-skilled organisations have very different remits, as SunOnline explains.
What does MI5 do and what are its limitations?
MI5 is widely understood to focus its intelligence efforts inside the UK but that isn't always the case.
With threats to Britain's security often coming from abroad, the agency says it does "work outside the UK where it’s necessary to protect the UK's national security or to counter security threats".
It describes itself as a "publicly accountable civilian intelligence organisation", not a "secret police force", as it does not have the power to arrest people.
Reporting to the Home Office, it was formed in 1909 under British army captain Vernon Kell to identify and counteract German spies in the country, according to the .
MI5 was renamed to the Security Service in 1931 when it merged with Scotland Yard's Special Section, which had similar responsibilities.
From 1909 and throughout the war, MI6 had several names including the "Foreign Intelligence Service", the "Secret Service" and the "Special Intelligence Service".
Its official origins go back to the start of the Second World War when it was adopted as a "flag of convenience", .
It adds: "Although 'MI6' officially fell into disuse years ago, many writers and journalists continue to use it to describe SIS."