UK will not be safe from ISIL until their 'virtual caliphate' is destroyed, warns Theresa May's security adviser

Britain will not be safe from Islamic State terror attacks until the extremists’ are stopped from spreading propaganda online, one of the Prime Minister’s top security advisers has warned.

Patrick McGuinness said that as the remnants of the area under the militants’ caliphate are swept from Iraq and Syria, the web has now become the front line against the group. 

Counter terrorism experts told a conference at the Royal United Services Institute in London that the priority was to now destroy the “virtual caliphate” of Islamic State in Iraq and Levant (Isil).

Mr McGuiness, deputy national security adviser, said the speed at which vulnerable young Britons could now be radicalised and plan attacks made them almost impossible to stop.

His comments came as a senior European Union security official also warned of the prospect of jihadists using biological warfare or cyber weapons to cause havoc.

Mr McGuiness said: “Until Islamic state cannot occupy space online freely, we will not be safe.”

He said the speed at which people are “brought to violence” was now “almost too fast to catch without the most extraordinary intrusive surveillance techniques which are not going to be sustainable or acceptable in a Western democracy.”

Mr McGuiness called on web giants to do more to tackle the threat. Large companies such as Google had made promising steps towards taking down extremist content, but questioned if it was a high priority for them and “whether or not it is the A-team on this”.

He went on: “It is massively about the choice that the tech companies make as to what they have on their networks. He said the tech giants would need to use similar techniques used to battle online child sex abuse and fake news. “These companies have got it in them to resolve this issue substantially.”

A senior EU official also warned that homegrown radicalised attackers were a bigger threat than extremists returning from the Middle East and warned that Isil jihadists also known as Daesh, may one day be able to cause havoc with cyber or bio weapons.

Gilles de Kerchove, the European Union's counterterrorism coord inator, also suggested a “Daesh 2.0” may emerge after the fall of the caliphate as the militants join forces with al-Qaeda.

He said there was growing consensus among intelligence chiefs that foreign fighters who had travelled to Iraq and Syria to join Isil would either die there or flee to other “hotspots” as the caliphate collapsed.

The return of foreign fighters was expected to be a “trickle”, he said.

But he warned that home grown extremists could employ cyber and biological weapons to cause destruction.

He said it was “probably easier than before for a lone actor to perpetrate an attack with catastrophic consequences”.

The miniaturisation of bombs meant a plane could be blown up with 25g of explosive.

He also warned that advances in biological engineering meant jihadists may in future manufacture biological weapons, rather than homemade explosives.

An early issue of an al-Qaeda propaganda magazine offered instructions on “how to make a bomb in your mum’s kitchen”

He said: “What if anyone will have a similar article on how to process a virus in your mum’s kitchen?”

Jihadists could tap into networks of cyber criminals to develop or buy the expertise to launch a devastating cyber attack, he suggested.

He said: “I believe it wouldn’t be too difficult at some stage to buy the support of a Russian group of experts who knows how to do it.”