The Association of School and College Leaders (ASCL) has criticised Ofsted's announcement that it is to conduct unannounced inspections across England.

It revealed earlier this week that 40 schools have already been selected for the two-day no notice assessment "during a two-week window in September."

Ofsted said that most of the schools identified for these inspections have already been marked for "section 5" assessments this year.

The ASCL's general secretary Brian Lightman said that Ofsted lacks credible authority for pushing ahead with these unannounced inspections.

"Moving to no notice for routine inspections is unnecessary and would be counterproductive," he explained.

"It stifles creativity and treats professionals like naughty children. School leaders need to be held accountable, but at the same time inspection needs to be proportionate. Schools currently only receive half a day’s notice."

Mr Lightman added that a move to no notice inspections would weaken the government's policy of "encouraging the best school leaders to support other schools".

Sir Michael Wilshaw, chief inspector of schools in England and head of Ofsted, said that Ofsted's work is vital in getting to the "heart of any problems" in schools.

From discipline to safeguarding to poor leadership and governance and the promotion of  "a narrow, unbalanced curriculum", Ofsted is charged with identifying issues and working with stakeholders to come up with solutions.

"That’s why we’ve expanded the criteria for conducting unannounced inspections for the coming year," Sir Michael continued.

"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."

Ofsted states that no notice inspections will take place at schools where a significant decline in standards has been identified; where there are concerns about safeguarding; and the quality of leadership has been questioned.