London, UK - Home Secretary Jacqui Smith is to outline plans on Thursday to clamp down on Web sites that groom susceptible people for extremism and terrorism.
She will call for illegal, radicalising material on the Internet to be removed.
"Stopping people becoming or supporting terrorists is the major long-term challenge we face," Smith will tell Internet service providers during her first major speech on terrorism and radicalisation.
The government believes the Internet should not be a "no-go" area in its battle against terrorism, and will call on the help of service providers.
"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," Smith will say.
She told BBC radio that recent cases had suggested growing evidence that people may be using the Internet to spread messages and plan terrorism.
Last October, Scottish student Mohammed Atif Siddique was jailed for eight years for possessing and distributing terrorist material via the Web.
Last July, three other men were jailed after pleading guilty to inciting terrorism via the Internet in messages that advocated killing non-Muslims.
Among the areas to be looked at will be people drawn to extremism through chat rooms.
"An effective response to terrorism depends on us -- on the active commitment of individuals and communities to certain rights and responsibilities, to shared values which apply irrespective of religion or culture," she will say.
The government plans to spend more than 500 million pounds on funding security and counter-terrorism next year, rising to nearly 600 million pounds during the following two years.
It aims to work with the Muslim community, and with colleges and prisons in an attempt to increase community cohesion.
But the Muslim youth organisation the Ramadhan Foundation said it was concerned action was not also being taken against far right sites.
"There are many that promote hatred and violence against minority communities and thus they should be closed also," said Mohammed Shafiq, the foundation's director.
Experts doubt how effective any attempt to control the Internet can be and note that little research on the problem has been carried out.