Islamic fanatics are planning to infiltrate Britain’s Army and police forces to carry out brutal attacks, a chilling manifesto for terror used by Islamic State (IS) reveals.

The jihadi manual explains how the atrocities committed in the Middle East – including the brutal murders of British hostages David Haines and Alan Henning – are part of a wider strategy that includes plans to wreak mayhem in the UK.

The development comes after security sources revealed yesterday that thousands of terror suspects are being monitored in the UK. The Association of Chief Police Officers has also warned police officers about their personal safety in light of the threat from IS.

Author of atrocities: Influential Abu Bakr Naji, right, wrote the guide (left) that acts as a template for terrorism

Neither the Metropolitan Police nor the Ministry of Defence were willing last night to discuss the security procedures in place.

The 268-page terrorism guide called The Management Of Savagery reveals IS’s intention to:

Target tourists at locations across the Islamic world

Exploit the propaganda value of targeting Western journalists, and to try to capture oil workers

Strike the same strategic targets repeatedly in a bid to expose weaknesses in Western security.

The handbook also revealed that infiltration operations have been going on for years – meaning that a sleeper cell may already have get inside the MoD or a police force.

Written by influential jihadi Abu Bakr Naji, the guide has been carefully studied by the terrorist commanders in Syria and Iraq, who he tells: ‘Our battle is long and still in its beginning… However, its length provides an opportunity for infiltrating the adversaries. [We] should infiltrate the police forces, the armies, private security companies, sensitive civil institutions.’

Step-by-step jihad: Extracts from The Management Of Savagery, studied by commanders in Syria and Iraq

He added that there were ‘exuberant youth in large numbers seeking jihad. Their desire for martyrdom indicates a proper condition of faith; all that is required is instructional polishing within the movement. It is possible to divert some of them to work in the security apparatus for infiltrating institutions.’

The template for terrorism states that the method chosen to kill hostages should maximise shock value in the West.

BRITISH TROOPS BACK IN IRAQ British troops returned to Iraq this weekend – just weeks after David Cameron promised he would not deploy ‘boots on the ground’. A dozen soldiers from The Yorkshire Regiment will train the Kurdish army on how to use heavy machine-guns against IS. The troops are in the city of Erbil, 30 miles from the front line of the battle against jihadi forces. An MoD spokesman said: ‘The Defence Secretary has approved the deployment of a small specialist team of non-combat Army trainers.’ In August, Mr Cameron said: ‘We are not going to be putting boots on the ground. We are not sending in the British Army.’ Advertisement

In a section titled Blazing Battle, Bakr Naji writes: ‘We must make this battle very violent, such that death is a heartbeat away, so that the two groups will realise that entering this battle will frequently lead to death.

'The increase in savagery is not the worst thing that can happen now. Rather, the most abominable of the levels of savagery is [still] less than stability under the order of unbelief. Our enemies will not be merciful to us if they seize us. Thus, it behoves us to make them think one thousand times before attacking us.

‘The policy of violence must also be followed such that if the demands are not met, the hostages should be liquidated in a terrifying manner, which will send fear into the hearts of the enemy and his supporters.’

Experts said last night that the Management Of Savagery, which was apparently first published in 2004, is a ‘relevant document’ and that the actions it expects jihadis to follow are realistic.

‘Everything in the book is possible,’ said Afzal Ashraf, an IS expert at the Royal United Services Institute in London. ‘But obviously they would find it more difficult to infiltrate the Army and police in Britain than they found in Iraq, where much of these institutions simply morphed into IS.

‘The Management Of Savagery is a book for IS’s thinkers but less so the doers. Islamic State has also miscalculated – it thought that extreme violence would deter the West. In fact IS’s enemies have been emboldened to take action.’

Wreaking havoc: The manual explains how the atrocities committed in the Middle East – including the brutal murders of British hostages David Haines and Alan Henning (pictured) – are part of a wider strategy

The Management Of Savagery claims that the overwhelming military superiority of the United States and the UK has no value without the cohesion of each society and the support for action in the region.

As IS are convinced that this cohesion does not exist, they believe they can persuade Western powers to retreat if they show how they are prepared to use the most gruesome tactics.

We must make this battle very violent, such that death is a heartbeat away, so that the two groups will realise that entering this battle will frequently lead to death The Management Of Savagery

The book says: ‘If the number of Americans killed is one tenth of the number of Russians killed in Afghanistan [around 14,000 during its occupation in the 1980s], they will flee... They have reached a stage of effeminacy which made them unable to sustain battles for a long period of time and they compensate for this with a deceptive media halo.’

Bakr Naji asks also jihadis to target oilfields, sea and airports, tourist facilities and banking and financial services. He envisages ‘a very long war,’ advising commanders to spread small numbers of their forces across a large area of the world.

Bakr mocks the West’s use of air strikes given the mobility of IS and the likelihood that these attacks will inspire local uprisings.

He identifies other Muslim countries that should be the next to be conquered by fundamentalists, including Saudi Arabia, Pakistan, Yemen, Turkey, Jordan, Libya, Tunisia and Morocco.

A memorial for Alan Henning, who was beheaded by IS, will be held tonight at the British Muslim Heritage Centre in Manchester. Organisers said that £30,000 has been raised so far for Henning’s widow, Barbara, and their children.