Ofsted inspectors were ordered to leave one of Britain's leading further education colleges after clashing with senior staff amid allegations of unprofessionalism and aggressive behaviour on an inspection.
The dispute broke out at Newcastle College on Tyneside which has been previously rated "outstanding" in all areas by the quality watchdog.
They were ordered off the premises following a row over the alleged conduct of some of the inspectors and concerns among teaching staff that courses were not being adequately marked.
According to reports, Ofsted offered their inspectors counselling following the showdown last month.
Newcastle College, which has 25,000 students and is the alma mater of Ant and Dec and the X-Factor winner Joe McElderry, is part of the NGC organisation. NGC also runs Skelmersdale College in Lancashire and the Intraining company in Sheffield, which provides apprenticeships.
All three were being assessed by the inspectors having previously been considered "outstanding" in all areas. Newcastle College topped national league tables produced by the Department for Education for 16 to 18 achievement for three consecutive years. The Ofsted inspectors were eventually allowed to return but their preliminary report has since downgraded the majority of areas in the three establishments to "good" although some remained "outstanding".
NCG's chief executive Dame Jackie Fisher emailed staff to tell them that the inspection had not been "trouble free." She said: "Unfortunately the inspection came to an untimely end as a result of some troubling incidents."
The message continued: "We are planning to pursue with Ofsted some outstanding matters which may improve the grade profile. However, based on Ofsted's track record in listening to provider complaints, this must be viewed as unlikely, regardless of how strong our case is."
A spokesman for NCG said: "We are very concerned with the way the inspection was conducted and there were some troubling incidents which meant the inspection ended before it was complete."
An Ofsted spokeswoman said: "While Ofsted does not comment on individual complaints, we do take complaints very seriously, investigating each one rigorously and dealing with issues as quickly as possible."