WEBSITES that fail to stop terror-related and extremist content being spread online should be clamped down on and heavily fined, the police commissioner has said.

Anthony Stansfeld, police and crime commissioner (PCC) for Thames Valley, said the Government had to come down on hard on social media sites and search engines that allow ISIS propaganda to radicalise people online.

The PCC said guidelines should be set to inform large internet companies of ‘what is acceptable and what is not acceptable’ and to fine them for ‘allowing ISIS propaganda’ to be accessed.

The police boss’s comments come after a former Oxford schoolboy was jailed for six-and-a-half years last Friday after becoming an online ISIS extremist.

Former Oxford Spires Academy pupil Hussein Yusef, who was fostered in the city after arriving as an asylum seeker from Afghanistan in 2010, posted and shared terrorist-related content through Facebook.

A judge said the 20-year-old, who is believed to have lived in Cowley and was a keen cricketer for East Oxford and Wayfarers cricket clubs, ‘transformed’ into an ‘enthusiastic supporter’ of so-called Islamic State.

Mr Stansfeld said it was up to communities to report concerns about extremism, and said he agreed with Theresa May, who has urged firms such as Google, Facebook and Twitter to go ‘further and faster’ to stop the spread of terrorist material.

This includes, Mrs May said, the development of new technology to stop it from ever appearing online in the first place.

He added: “It’s very sad that people who seek asylum in our country and we generously give them asylum and we look after them, that they repay us by wanting to destroy and overthrow that very system and way of life.

“There is only so much that schools and other organisations can do [to prevent it].

“People are out of schools most of the time and some are naïve and are seduced by reading material online.

"It’s not going to go away. It is anywhere because people can access it by going online. We do not seem to be able to prevent it sufficiently.

“High numbers of people are hard-working and industrious but a small minority are not and are dangerous.”

The Oxford Mail revealed yesterday how Yusef was described as a ‘model student’ by his former headteacher Sue Croft.

He was convicted at Kingston Crown Court, London, for three terrorism offences.

Earlier this month reports said Internet giants had made efforts to clamp down on extremist content, with Google describing online extremism as a ‘critical challenge for us all’.

Facebook said it was working ‘aggressively to remove terrorist content’ from its website.

The global social media giant said it had developed a shared industry database of ‘hashes’ - unique digital footprints - which catalogues violent extremist videos or images.

Twitter said terrorist content had no place on its platform.