Al-Qa'ida has explicitly called for "cyber-jihad" and there have been a series of attempts by terrorists to "invade" Facebook, the Government's new counter-terrorism strategy said today.
Terrorists are increasingly using online technology to plan and disguise attacks and there will be more cyber-terrorism in the future, it said.
"Since the death of Osama bin Laden, al-Qa'ida has explicitly called not only for acts of lone or individual terrorism, but also for 'cyber-jihad'," it added.
The use of social networking sites and video sharing is now "commonplace", the strategy said.
"There have been a number of attempts by terrorist and extremist groups to 'invade' Facebook," it added.
"Twitter will be used to re-post media or forum articles enabling extremist content to be shared more quickly, widely and amongst people who would not normally search for extremist content."
The strategy comes the day after the UK threat level from international terrorism was downgraded from severe to substantial, meaning there is still a "strong possibility" of an attack and one may well happen without further warning.
Launching the Government's counter-terrorism strategy, Home Secretary Theresa May said: "Advances in technology mean our response must improve to keep pace.
"Terrorists are increasingly using online technology, including Google Earth and Street View, for attack planning."
She went on: "The marauding attacks in Mumbai in 2008 were directed by people using off-the-shelf secure communications technology to stay in contact with each other.
"Software to encrypt mobile phone voice and text functions is widely available and improving.
"Peer-to-peer networks can be used to distribute files and information rapidly and securely.
"And cloud computing offers new means for storing, sharing and distributing material online.
"It can be encrypted and configured to work with mobile devices, leaving little or no trace of the data behind.
"And while radicalisation continues primarily to be a social process, terrorists are making more and more use of new technologies to communicate their propaganda."
Mrs May added: "To tackle these new and emerging threats, our own technology must constantly evolve and adapt."
Mrs May said the Government will "work much harder to tackle the particular challenge of radicalisation on the internet".
She added that the UK must also learn lessons from previous attacks, including the July 7 bombings in London in 2005 and the Mumbai attacks in 2008.
"We must learn lessons from attacks that have happened elsewhere and prepare for the possibility that they could be replicated here."
Police firearms officers now have access to higher calibre weaponry, "enhanced tactics and training to deal with this kind of assault".
The Home Secretary also said the Government was looking at ways to narrow the gap between the number of suspected terrorists and the number of people arrested and prosecuted.
Post-charge questioning will be allowed in cases where further substantial evidence emerges after charges have been brought, the strategy said.
"This will permit questioning of people about the offence for which they have been charged and enable prosecutors to build more robust evidential cases or explore further lines of inquiry in relation to an ongoing investigation.
"We believe that bringing in these changes was not given sufficient priority in the past."Reuse content