Ofsted has begun an unannounced inspection at a school where there have been two days of walkouts over staff safeguarding concerns.
Inspectors went in to Starbank School in the Yardley area of Birmingham on Tuesday, and were at the site again on Wednesday.
They will be publishing their findings in due course, Ofsted added.
The move followed two separate days of industrial action by members of the NASUWT union which had called for a knife audit at the school, and cited poor behaviour from pupils.
On Wednesday, staff and teachers staged the second of two days of strikes.
However, there was no picket line as the union said members were meeting privately to discuss “all the outstanding issues” which remain unresolved between them and school leaders and Birmingham City Council representatives.
Last week, about 20 members of the NASUWT joined a picket at the school’s Hob Moor Road site to express their concerns about pupil “indiscipline” and staff safeguarding measures.
The action came following reports a 12-inch knife had been brought into the school, and a separate incident where a member of staff is said to have been assaulted.
The school, rated outstanding by Ofsted in May 2012, is also reported to have a problem with pupils fighting each Thursday.
In a statement, Ofsted said: “(Inspectors) began an unannounced inspection of this school yesterday.”