MI5 struggling to deal with 500 live terrorism probes

BRITAIN’S overstretched security services are managing a staggering 500 active terror investigations, senior Whitehall sources said yesterday.

They have foiled five plots in the last two months alone and are investigating around 3,000 ‘subjects of interest’ – or possible terrorists.

Defending accusations that MI5 had missed repeated warnings about Salman Abedi, the source emphasised the scale of the job facing counter-terrorism officials.

The source revealed the bomber, 22, was among a ‘larger pool’ of former ‘subjects of interest’ on MI5’s radar and the risk he posed was subject to review.

Deciding whether to monitor a person around the clock relies on ‘difficult professional judgements based on partial information’, the source stressed.

Officials said 18 plots had been thwarted since 2013. Five had been disrupted since the Westminster attack on March 22, compared with 13 in the three years before.

As the security services faced questions about how the Manchester bomber was able to slip through the net, a Whitehall source pointed to the ‘unprecedented scale of threat’. Britain’s security services are considered among the world’s best but are struggling to monitor the flood of potential terrorists returning from Syria and Iraq.

A senior Whitehall source said: ‘MI5 is managing around 500 active investigations, involving some 3,000 subjects of interest at any one time. Abedi was one of a larger pool of former SOIs whose risk remained subject to review by MI5 and its partners.

‘Where former SOIs show sufficient risk of re-engaging in terrorism, MI5 can consider re-opening the investigation, but this process inevitably relies on difficult professional judgements based on partial information.’

Earlier in the week Home Secretary Amber Rudd admitted that Abedi was ‘known’ to the security services.

Counter terrorism agencies were facing questions after it emerged he was repeatedly flagged to the authorities over his extremist views but was not stopped.

It is understood he told friends that ‘being a suicide bomber was OK’, prompting them to call the Government’s anti-terrorism hotline. There were suggestions the authorities were told of the danger posed by Abedi on at least five occasions in the five years prior to the attack.

More than 3,000 jihadists are thought to be in the UK, stretching the security services to breaking point. Up to 30 officers are required to provide 24-hour monitoring of just one suspect. Restricted resources mean MI5 can watch around 50 suspected terrorists around the clock.

Spies and counter-terror police are struggling to monitor the flood of suspects, mainly radicalised men and women in their teens and early 20s. About 850 Britons are thought to have gone abroad to fight with so-called Islamic State as it took control of large swathes of territory in Syria and Iraq.

But with the terror group being pushed out, extremists with British passports are fleeing back to the UK where authorities fear they may unleash a new wave of attacks.

Although more than 100 have been killed, around half have returned home with battle experience and training in the use of explosives and firearms.

The RAF is targeting UK jihadists in Syria and Iraq to stop them coming back to the UK and plotting attacks against Britain from the warravaged nations.

In October 2015, MI5 director-general Andrew Parker said the threat from jihadists was on a scale he never seen in his 32-year career.

‘Unprecedented scale of threat’ ‘Stretched to breaking point’