- Out of 583 jailed in UK for terror offences since 2001, 418 now out again
- Three were sentenced to life and 24 were serving more than four years
- At least four of them were people who helped the 21/7 suicide bombers
The vast majority of terrorists convicted in Britain since 9/11 have already been released from prison and are back on the streets, it was revealed today.
Out of a total of 583 jailed in the UK for terror offences since 2001 around 418 have been released again, including three who were given life sentences.
This group, 164 of whom walked free since 2014, included several people who helped the suicide bombers who failed to blow themselves up in London three weeks after 7/7.
Out: Adel Yahya and Ismail Abdurahman were both jailed for their part in the 21/7 plot - either helping a suspect afterards or collecting information for them - and both are now free men
New research by Sky News found that 104 left prison after serving between a year and four years, while 24 were released after more than four years.
Some are understood to have been released without agreeing to take part in anti-radicalisation classes while behind bars.
Omar Khyam, who was jailed for a plot to blow up a shopping centre and nightclub in Kent with homemade bombs, is among the two thirds of extremist prisoners who refused to change their views.
Former jihadi Hanif Qadir who now runs a counter-extremism outreach said deradicalisation in jails is 'failing miserably'.
He said: 'There are experts out there that are equipped and able to tackle the problem but they are not the ones that are doing it in prison.
'At the moment the prison imams, God bless them, they're not adequate and they're not experienced enough to tackle the problem of radicalisation within prisons.'
Lord Blunkett, who was Labour's Home Secretary when many were jailed, told Sky News: 'It's perfectly reasonable to say that once someone's served their sentence, if it isn't possible to reassess them, we should continue to monitor them outside prison.
'So, if there's any indication at all that they are reconnecting with organised terrorist groups, the intervention can take place very quickly rather than allowing them to commit another act and then having to try to pick them up again.'
At least four criminals jailed for their part in the 21/7 plot have been freed, with some moved to hostels or council properties.
Adel Yahya, who admitted collecting information useful to terrorists and jailed for six years and nine months in November 2007.
He is believed to have been freed by 2010.
Yeshi Girma knew of husband Hussain Osman's plan to blow up a Tube train but did nothing. She was secretly freed in 2013.
Ismail Abdurahman was released from prison after just three years behind bars for helping the July 21 bombers in 2005.
He was moved to a bail hostel after winning an appeal against a bid to send him to Somalia. This year the British Government was ordered him more than £13,000 because his human rights were 'violated' during police interviews over a plot to attack London.
Zahoor Iqbal, 35, Mohammed Irfan, 36 and Hamid Elasmar, 49 were freed and living in Birmingham despite being linked to a plot to slaughter a serviceman 'like a pig'.
It came as the head of MI5 has warned that the police and security services will not be able to stop all terrorist attacks on Britain despite their successes in recent years.
Andrew Parker, director general of the domestic intelligence agency, revealed yesterday that 12 terrorist plots in the UK had been foiled since 2013. However, he warned that Islamic State posed the biggest current threat to national security and it would last a generation.
'Together with MI6, GCHQ and the police, MI5 has disrupted 12 plots in the UK since June 2013,' said Mr Parker.
'ISIL (Islamic State in Iraq and the Levant) is an enduring threat, here to stay, and is at least a generational challenge. MI5 and the intelligence agencies have good defences because of the investment made in our capabilities. We will find and stop most attempts to attack us, but not all.'
In a keynote speech at the Royal Society he said MI5's technological expertise 'makes it less likely people will be killed by terrorism or our secrets will be stolen'.
His speech came just hours after Britain's counter-terrorism police chief warned of the threat of a Paris-style gun rampage in Britain as he said half of the terror plots foiled involved suspects trying to get guns.
Mark Rowley said five plots uncovered in the past two years involved fanatics trying to amass machine guns and others firearms to launch an attack on our streets.
Assault weapons like the ones used in the Paris massacre last November are being smuggled into Britain by criminal gangs from the Balkans and Eastern Europe and could be sold on to terrorists, he said.