The threat from homegrown jihadis has reached unprecedented levels after ISIS ordered their followers to carry out deadly attacks in Britain rather than Syria, it was claimed today.

The terror group 'very cleverly switched tactics' by winding down efforts to lure British extremists to the fight on the frontline, Security Minister Ben Wallace said.

Instead they are throwing their efforts at radicalising people through the internet and ordering them to slaughter fellow Brits in truck attacks at home.

The stark warning comes after dozens of people were murdered and many more injured after four terror attacks in just three months in London and Manchester.

Meanwhile Max Hill QC, the independent reviewer of terrorism legislation, has called for tougher sentences for those peddling extremist propaganda.

He also called for internet giants like WhatsApp to end encryption of anonymous messages to combat terrorism.

security Minister Ben Wallace (pictured left) and Max Hill QC (pictured right) the independent reviewer of terrorism legislation, both said the nature of the terror threat facing Britain has changed with jihadis increasingly radicalised online in their bedrooms and encouraged to carry out attacks in the UK instead

Hundreds of floral tributes are left outside Borough Station in London, where eight people were killed when three jihadis drove their van into pedestrians in nearby London bridge before leaping out and stabbing innocent people enjoying a night out. It was one of four terror attacks on British soil in just three months

Terror chiefs said the mass return of jihaids who have travelled abroad to fight for Islamic State (also known as ISIS and Daesh) has not materialised.

More than 800 British radicals have travelled to Iraq and Syria to fight for the barbaric group, according to estimates.

Around 200 are thought to have been killed on the frontline, while another 350 have already returned, according to Sky News.

But many others remain out there too scared to return to Britain in case they are caught and locked up.

Mr Wallace told Sky News: 'ISIS have very cleverly switched tactics. They have realised that they can't get the supply of fighters into Syria and Iraq, and indeed they have been defeated, predominately , in Iraq.

'And at the same time they need to carry on trying to spread terror.

'So what we have seen them do is use more inspiration, use the internet, to radicalise those people and say ' take action at home and do whatever you can to really kill people'.

Sky News said the threat from homegrown jihadis has reached unprecedented levels.

Mr Hill QC said there has been a fundamental shift in how people are radicalised, with Brits targeted online and through social media rather than 'face to face'.

He told the broadcaster: 'It is very hard to detect a lone individual sitting in a darkened room with a laptop who has a predisposition, perhaps, to some violence, perhaps some low level criminality.

'And over quite a short period of time emerges into a radicalised mindset and then rents a van and then plans or carries out an atrocity.

British jihadi Khalid Masood drove his car into pedestrians on Westminster Bridge, killing several, before leaping out and storming the grounds of Parliament where he murdered PC Keith Palmer. It was the first in a series of remarkably similar terror attacks on Britain this year

The Queen speaks to Millie Robson, 15, as she visited victims of the Manchester terror attack in after British suicide bomber Salman Abedi blew himself up at an Ariana Grande concert. He killed 22 people and injured dozens more in the carnage

'Of course that is very hard to detect.

'Whereas a decade ago we tended dot see physical radicalisation, face to face, we know now that the proliferation of extreme propaganda on the internet and on social media means that sort of material is generally available to individuals who may be predisposed to thinking in certain ways.'

In a separate interview with the Evening Standard, he called for an end to encryption and tougher terror sentences.

He ruled out 'sledgehammer' new laws and called for tech giants such as Google and Facebook to introduce 'verification' checks on social media users.

He said: 'The vast sums of money that tech companies generate … means that we should all be looking to those companies to recycle some of those profits into the fight to take down extreme material.'

On sentencing, he added: 'We are seeing some very hard examples of radicalisation that is swift, online, and involves almost no face-to-face contact between radicalisers and those who are vulnerable to the extremist message.

'In those circumstances… we should think again about sentencing.'