Home Secretary Jacqui Smith has urged internet service providers (ISPs) to ban websites that promote terrorism.

Speaking at the launch of the International Centre for the Study of Radicalisation and Political Violence, Smith said the Government needed to target extremists who groom vulnerable targets online.

Among the areas to be looked at will be people subjected to extremist views in chat rooms, which the Home Secretary said could lead to them becoming involved with extremist groups. ISPs will also be expected to remove or block any Al-Qaida or extremist website material.

“We are already working closely with the communications industry to take action against paedophiles. I believe we should also take action against those who groom vulnerable people for the purposes of violent extremism. Where there is illegal material on the net, I want it removed," Smith said.

However, internet rights groups and the Internet Services Providers' Association (ISPA) have said the proposals could be unworkable.

The ISPA told Computeractive: "It’s hard to identify what is legal and illegal content on the internet. ISPs can’t play judge and jury about what’s right and wrong. Human rights and free speech must be a consideration here.”

Dr Yaman Akdeniz, a law lecturer at Leeds University and director of the Cyber Rights organisation, agreed: “The difficulty is where you draw the line. When does speech become extreme or for that matter racist?”

Both organisations also said plans by Smith to get ISPs to block these sites could be problematic.

“Many of these sites are based outside of the UK and as a result UK ISPs would not have the power to block these,” said the ISPA.

Dr Akdeniz also warned that this could also encourage extremists to go underground making “detection and monitoring of such groups and individuals more difficult by the law enforcement and security agencies”.