Snap checks at dozens of schools
Ofsted inspectors have been sent to dozens of schools across England to conduct snap inspections amid serious concerns about standards.
Around 40 schools are to receive no-notice visits over a two-week period, the inspectorate said.
The wave of unannounced visits are being carried out under Ofsted's existing powers. Schools usually get half a day's notice of an inspection.
In the wake of reports into the alleged "Trojan horse" takeover plot by hardline Muslims at a number of Birmingham schools, Ofsted chief Sir Michael Wilshaw said that he would look again at routine unannounced inspections, a move that was first mooted around two years ago but later dropped amid strong opposition from school leaders.
While these plans are under consideration, Sir Michael said he would be asking Ofsted's regional directors to make use of the watchdog's existing powers to conduct no-notice inspections where there are concerns about rapidly declining standards, keeping pupils safe - including a decline in students' behaviour - leadership and governance and the breadth and balance of the curriculum.
Many of the schools chosen for a no-notice inspection were due to receive a visit this term, but others have been selected because there are concerns about their performance.
Sir Michael said: "Parents rightly expect Ofsted inspections to get to the heart of any problems that may exist in a school - whether they are to do with discipline, safeguarding, poor leadership or governance, or a narrow, unbalanced curriculum. That's why we've expanded the criteria for conducting unannounced inspections for the coming year.
"I'm currently giving thought to whether Ofsted should move to more routine no-notice inspections as part of our wider education inspection reforms, which we will be consulting on later this year.
"In the meantime, under our regional structure, inspectors are well placed to use their local knowledge and contacts to identify where these sorts of problems may be taking hold so we can respond swiftly and report publicly on what we find."
No-notice inspections will continue throughout the year, Ofsted said, with findings published on the inspectorate's website.
Education Secretary Nicky Morgan confirmed in July that Ofsted is to consult on introducing no-notice inspections for all state schools in England as she announced a raft of new measures designed to address the situation in Birmingham.
Four separate probes were conducted into the allegations in Birmingham, which were originally sparked by the ''Trojan Horse'' letter - now widely believed to be a hoax - which referred to an alleged plot by hardline Muslims to seize control of a number of school governing boards in the city.
In June, Ofsted issued a damning verdict on the running of a number of Birmingham's schools and declared five failing, placing them into special measures.
These schools were: Golden Hillock School, Nansen Primary School and Park View Academy - all run by the Park View Educational Trust (PVET), as well as Oldknow Academy and Saltley School. A sixth, Alston Primary, was already in special measures.
Ofsted said today that inspectors have made their first return visits to the five schools involved to check that the problems identified are being addressed.