David Moore, Her Majesty's inspector responsible for overseeing pupil behaviour, discipline and bullying, spoke out as more and more colleges are offering courses for 14 and 15-year-olds.
He acknowledged it was a solution for some children, but told council education chiefs that colleges were able to cope with difficult youngsters because there were relatively few of them.
"If it becomes a common solution, then it would become difficult to manage, " he warned the Association of Chief Education Officers. "While it is a small experiment, it stands a chance. If you overload the system, then it is questionable whether the staff feel trained sufficiently to manage."
He was also concerned about the standard of courses offered after cutting out pictures from a magazine in a personal and social education class.
More and more colleges are now taking in pre-16s and there is a fear among some lecturers that further education has become the new dumping ground for disaffected teenagers. The idea of college for 14-year-olds, however, was proposed last year by Sir Ron Dearing to stop them slipping through the education and training net.
Wirral College has been in the vanguard of those offering programmes for pre-16s, and has 500-600 14 and 15-year-olds on roll. Fifty have been excluded from school. The rest are either school-phobic or those who it is believed will do better in college.
Principal Jenny Shackleton said: "The 14 and 15-year-olds can cause problems, but by and large they aren't much more difficult than some of the more difficult 16 and 17-year-olds."
At Wirral, the pre-16s make up less than 3 per cent of the student roll, the LEA continues to have responsibility for the pupil, and the college gets part of the money that would have gone to the school.
Ms Shackleton said: "Because we are a very large college of all ages and stages we can offer the equivalent of a family setting - and every family has a few truanting youngsters."