Teenagers are a prime target for terrorist recruitment and colleges are among their hunting grounds, the Government claimed as it published a report aimed at countering violent extremism.
The Department for Innovation, Universities and Skills justified focusing on risks to Muslim students in Learning Together To Be Safe by claiming groups linked to Al-Qaeda actively sought recruits at colleges.
It also quoted Jonathan Evans, director-general of MI5, saying: "As I speak, terrorists are methodically and intentionally targeting young people and children in this country. They are radicalising, indoctrinating and grooming young people to carry out acts of terrorism."
The youngest person convicted of terror offences, Hammaad Munshi, who last year was sentenced to two years in a young offenders' institution for compiling information likely to be useful to terrorists, was 15 when he was recruited.
Some of those convicted of the 2005 London bombings were former FE college students, although there is no proof that this was a factor in their radicalisation.
The Association of Colleges welcomed the advice but said it had no evidence of active recruitment to extremist groups on campuses.
Despite a more conciliatory approach than the first draft of guidance for higher education, which prompted a revolt by the University and College Union, lecturers feared the emphasis on Islam would harm relations with Muslim students.
Sally Hunt, UCU general secretary, said: "The Government's laudable plans for community cohesion will be damaged by emphasis in the guidance on targeting colleges with large numbers of Muslim students.
"The guidance acknowledges a bigger problem is gang violence."