Facebook left horrific Islamic State videos on its site for three years, the Daily Mail can reveal.

Despite repeated criticism of the social media giant for failing to protect users, the infamous Cubs Of The Caliphate film posted in March 2015 was one of several that could still be viewed until last week.

Facebook claims to have cracked down on hate content but the video and other sickening IS propaganda was not removed until a detailed complaint from the Mail. Thousands of users have watched the video, which shows a young boy – pictured – shooting dead a teenage hostage.

Facebook left horrific Islamic State videos on its site for three years, the Daily Mail can reveal

Other IS material which was on Facebook for over two years includes masked terrorists carrying out mass beheadings of Christians and knifemen warning: ‘You will not have safety, even in your dreams, until you embrace Islam.’

A bomb tutorial used by Manchester Arena bomber Salman Abedi was repeatedly uploaded.

Experts fear there is a deliberate attempt to use Facebook to target potential British jihadi recruits. Former UK counter-terrorism chief Sir Ivor Roberts said the failure to take down the videos was ‘chilling and inexcusable’.

He called on the Home Secretary to take urgent action and suggested that a major factor is Facebook’s refusal to use technology that prevents extremist videos from being reposted repeatedly.

Despite an avalanche of criticism over its alleged failure to protect users, Facebook has recently trumpeted its ‘significant strides’ in finding and removing large amounts of Islamist propaganda. It insists the ‘vast majority’ of terrorist propaganda is removed automatically, without the need for someone to report it first.

But last month the Mail found it easy to access a string of horrific videos, including the one in which a boy, aged around ten, executes a 19-year-old Israeli-Arab accused of being a Mossad agent.

Facebook claims to have cracked down on hate content but the video and other sickening IS propaganda was not removed until a detailed complaint from the Mail

A 29-minute video showing the shooting and beheading of Christians by an IS affiliate in Libya had been on Facebook since April 2015.

Sir Ivor, former head of counter-terrorism at the Foreign Office and now an adviser to the Counter Extremism Project, said: ‘Facebook’s recent series of apologies and assurances that they will take action to protect their users is clearly fake news.

‘The existence of this video on Facebook for three years proves that they are not doing all they can to protect users and prevent them from viewing extremist content.

‘This is just one of a large number of videos researchers at the Counter Extremism Project have identified.

‘It is well known that IS specifically targets Britain for potential recruits. It is chilling and inexcusable that whatever Facebook is saying publicly, our research shows that extremists in this country can still be radicalised in that way.

‘Self-regulation does not work and the UK’s new Home Secretary Sajid Javid must stand strong and impose regulations on these companies.’

Facebook has said new methods were quickly detecting and removing such propaganda.

It removed nearly 1.9million terror-related items in the first three months of this year. But the company, which is worth billions, employs only 200 staff to weed out such material.

A Facebook spokesman said: ‘We work aggressively to make Facebook a hostile place for terrorists and to combat extremism on the platform. The videos reported to us by the Daily Mail have been removed.’