MINI-inspections are planned for the best colleges, says the Ofsted watchdog.

It has suggested a one or two-day inspection leading to a short inspection report, instead of a full inspection, for up to 30% of colleges in plans out for consultation.

If colleges are judged outstanding or good they will not be inspected for four years, providing they maintain standards.

All colleges have been visited every year since September, 2005.

All outstanding and good colleges would still face annual checks from inspectors under the plan, which signals greater self-regulation for the further education sector.

An Ofsted spokesman said: "We recognise that further education performance is improving, with learner success rates now averaging 75%, compared to 60% in 2001."

Mike Harris, the Institute of Directors' head of education and skills, said inspection proportionate to risk "can work well", but warned: "Other alignments with school inspections should be avoided.

"Paring back the inspection regime too far dilutes its value.

"This leads to a loss of detailed information, hampering comparisons of performance over time and placing a heavy responsibility on often- shaky self-evaluation procedures.

"The visibility of excellent provision could be obscured.

"Equally crucially, there continues to be insufficient emphasis on the role that Ofsted should play in supporting improvement."