Fears have been raised about online extremism a year after the death of soldier Lee Rigby as deadly jihadist material remains widely available online.

The young soldier was mown down in a car and hacked to death on May 22 in London last year by Muslim fanatics Michael Adebolajo and Michael Adebowale, prompting a Government task force to propose greater powers to block access to extremist websites.

Yesterday MP Keith Vaz, chairman of the Home Affairs Select Committee, called for renewed efforts to combat the murderous material with schemes to spread more moderate ideas and stop Muslims falling into the clutches of radicals.

Mr Vaz said: "It is vital that horrific events such as these never happen again."

Experts say the internet is giving fanatics much wider opportunities to radicalise worshippers, having migrated from more traditional means of preaching in person. "Internet-based and peer-led counter-extremism projects hold the key," added Mr Vaz. "We must engage with the communities and grow counter messages organically in the same way extremist messages are expounded."