The Education Secretary has backed Ofsted’s “one-word assessments” despite calls from teachers for the system to be abolished.

Gillian Keegan said the ratings, which range from “outstanding” to “inadequate”, are “clear” and “easy for parents to navigate”.

Pressure on the schools watchdog in England continues to mount as unions demand an immediate freeze of inspections to allow for full mental health assessments to be carried out on teachers.

They're clear. They're simple to understand

It comes after Ruth Perry, headteacher at Caversham Primary School in Reading, Berkshire, killed herself in January while awaiting an Ofsted report which downgraded her school from the highest rating to the lowest.

Touring broadcast studios on Monday, Ms Keegan described Ms Perry’s death as “tragic” and said His Majesty’s Chief Inspector is looking at whether the way the regulator works with schools can be improved.

But she insisted “undermining Ofsted” is “not the right approach”, describing the role it plays in upholding standards and safeguarding as “crucial”.

“I know His Majesty’s Chief Inspector is looking at this following the tragic case of Ruth Perry, which is tragic and our thoughts do go out to her family and friends and her school community,” she said.

Asked if she supports Ofsted’s single-word assessments, Ms Keegan said: “Yeah. They’re clear. They’re simple to understand.”

She added: “There’s quite a broad framework that’s assessed as part of Ofsted and they’ve actually looked to broaden that framework even more.

We always want inspections to be constructive and collaborative, and in the vast majority of cases school leaders agree that they are

“Of course, if there are areas that needed to develop further then that is where the right conversation to have is.”

Critics argue single-word ratings fail to reflect the complexity of a school and the quality of its teaching.

Paul Whiteman, general secretary of school leaders’ union NAHT, said: “One-word Ofsted grades have clearly now had their day. While they may appear simple to understand, they are not reliable and at worse can give an incomplete and inaccurate picture of a school’s performance.

“It is impossible to accurately describe something as complex as a school in just a single word, and it’s worrying that ministers think this can be done.

“There is also growing evidence that parents no longer value these overly simplistic judgments and would value a more balanced, descriptive approach. It is time to move on from this outdated and unreliable system.”

It comes a week after a motion calling for Ofsted to be abolished was approved at the NASUWT’s annual conference in Glasgow.

The National Association of Head Teachers (NAHT) has also indicated it could take legal action against the watchdog after it did not suspend inspections following Ms Perry’s death.

The motion carried by the NASUWT union acknowledged the “perceived demands of Ofsted are the major contributor to the excessive workload and bureaucracy that blights the lives of teachers”.

An Ofsted spokesman declined to comment on the NASUWT’s proposals but said: “Inspections are first and foremost for children and their parents – looking in depth at the quality of education, behaviour and how well, and safely, schools are run.

“Our inspectors are all former or current school leaders who fully understand the pressures of the role. We always want inspections to be constructive and collaborative, and in the vast majority of cases school leaders agree that they are.”