MPs have criticised Ofsted chief inspector Amanda Spielman for not speaking out more about issues facing the school sector.
A new report by the Commons Public Accounts Committee claims Ofsted does not make the most of its position to use intelligence from inspections to be a force for school improvement.
And it attacks Ms Spielman for not giving her views on the wider school system when she appeared before MPs earlier this year.
The chief inspector hit back, saying that her job is to provide Parliament and the education secretary with “an evidence-based appraisal of educational standards”.
She said that when Ofsted does have evidence, she has spoken out on a range of issues, including the risk of radicalisation and the narrowing of the curriculum.
The PAC report says: “[Her Majesty's] chief inspector has a statutory role to advise the secretary of state for education on the quality of schools.
Ofsted chief 'in an ideal position to speak freely'
"Her independence and status as the head of a non-ministerial government department puts her in an ideal position to speak freely, without fear or favour. Inspectors are on the ground in schools every day, witnessing the challenges that schools are facing and the underlying causes of poor performance.
“Ofsted should be sharing these insights with the department and more widely.”
The committee also says it was disappointed that Ms Spielman did not provide “clearer or more direct answers" when asked about the impact of funding pressures on the breadth of the curriculum, and concerns about pupils' mental health and wellbeing.
It has called on Ms Spielman to write to the committee by next month with “her reflections on the main risks to schools' effectiveness and the systemic cause of poor performance, including the impact of funding pressures”.
Ms Spielman said: “I understand that the committee is disappointed that I would not be drawn into giving my views on some wider issues in the sector. My role is to provide Parliament and the secretary of state with an evidence-based appraisal of educational standards.
"It would be irresponsible of me to make comment on those areas where we do not have clear evidence of the impact on standards or young people’s wellbeing.
“Where we do have that evidence, be it about the dangers of illegal unregistered schools, the risks of radicalisation, the narrowing of the curriculum or the importance of early literacy, I have not hesitated to speak out and will continue to do so.”
It is not the first time Ms Spielman has faced criticism following an appearance before MPs.
In 2016 the Commons Education Select Committee refused to endorse her as the next head of Ofsted after she appeared before the committee.
She became Ofsted chief inspector last year, replacing Sir Michael Wilshaw.
The PAC report, published today, also warns that Ofsted's credibility “will evaporate” if the level of school inspections continues to be cut back.
The PAC found that Ofsted had been more focused on the cost of school inspections than on getting assurance about schools' effectiveness.