Online video giant YouTube has been condemned for failing to take down extremist content including films praising Adolf Hitler and Taliban propaganda.
An extensive study of Islamist and far-right extremist material shared on the website found more than 120 videos were not removed even after they had been flagged to the site’s administrators.
Yvette Cooper, chairwoman of the influential Commons Home Affairs Select Committee, said it was “simply unacceptable” that some content remained live weeks after being reported.
The Labour MP commissioned the study by foreign policy and security think tank the Henry Jackson Society, which involved monitoring YouTube over almost three months.
During the study, researchers flagged up 107 Islamic extremist videos and 94 examples of far-right content.
But 61 of the far-right videos and 60 of the Islamic extremist posts remained online for viewers to watch.
A video entitled Adolf Hitler Was Right, featuring praise of the Nazi leader over images of Jewish families being taken to concentration camps, was flagged on August 1 but was still live on September 18.
Promotional material from the Taliban was flagged on August 29 but still available on September 18.
Other videos still available despite being reported included footage of a child singing over images glorifying terrorism, a man filmed slapping a Muslim teenager with bacon while shouting “Isis scum” and a video of burning buses celebrating the deaths of Shia Muslims.
Ms Cooper said: “It is simply unacceptable that YouTube are taking so long to remove material that contains images and content that glorify extremist violence. Whether that’s Islamic extremism or far-right extremism, the reality is that this material is far too easy to access.
“We know social media can play a role in the radicalisation of young people, drawing them in with twisted and warped ideology.
“YouTube have promised to do more, but they just aren’t moving fast enough. Google, which owns YouTube, is one of the richest and most innovative companies on the planet. They have the resources and capability to sort this and they need to do so fast.
“And we need much stronger action from Government. We’ve had ministerial summit after ministerial summit but it just isn’t making enough difference. We now need proper penalties and fines for social media companies who do not act swiftly enough to remove dangerous and illegal content.”
Henry Jackson Society executive director Alan Mendoza said analysis of Islamist terrorist offences found that in 35% of cases, the internet was cited as a major way in which offenders engaged with extremism.
He said: “These ideologies can be freely disseminated and amplified online and there is room for improvement by technology firms to provide spaces to expose and debate their inconsistencies.”
YouTube defended its approach to extremist content, claiming many videos are now removed before any complaint is received as a result of its monitoring systems.
A spokesman said: “Addressing the challenge posed by extremism is a critical challenge for us all and we’re determined to be part of the solution.
“We’ve put our best talent and technology to the task and we’re making progress through new machine-learning technology, partnerships with experts and collaborations with other companies through the Global Internet Forum.
“Through new uses of technology, the majority of videos we removed for violent extremism over the past month were taken down before receiving a single human flag. We’re doing more every day to tackle these complex issues.”