Education Secretary Michael Gove has suggested some schools judged to be "outstanding" do not deserve the accolade.
He complained that schools were given an overall top rating by inspectors even though the standard of teaching there was not judged to be outstanding.
Mr Gove said this was a "worry" and he would ask the new chief inspector of England's schools to look at the issue.
Head teachers say the top ratings are well-deserved.
Schools are rated in various categories and are then given an overall ranking.
They can be judged to be outstanding, good, satisfactory or inadequate.
In a speech earlier this week Mr Gove said: "It is a worry to me that so many schools are still judged as 'outstanding' overall when they have not achieved an 'outstanding' in teaching and learning.
"I intend to ask the new chief inspector to look at this issue and report back to me with recommendations."
Figures from Ofsted show that about one in 10 of England's secondary schools - 600 or so - are judged to be outstanding overall.
But just over half of those schools (53%) are not rated outstanding for teaching and learning.
Primary schools are less likely to get an outstanding rating if they do not have the top ranking for teaching and learning.
This is true of 18% of the top-rated primaries.
Ofsted insists inspectors place high importance on the the quality of teaching.
A spokeswoman said: "Teaching and learning are central to Ofsted's school inspection.
"The judgement on teaching will always be a key consideration when inspectors judge overall effectiveness of a school."
The schools inspection system in England is being shaken up. From January, schools will be judged on just four areas instead of the existing 27 categories.
These will be pupil achievement, quality of teaching, leadership and management and the behaviour and safety of pupils.
Under other changes, outstanding schools are no longer going to be routinely inspected. They will face inspections if concerns are raised about them or if grades fall dramatically.
Brian Lightman, the general secretary of the Association of School and College Leaders, said Mr Gove seemed to be "pre-empting the work of Ofsted" and suggesting that there should be "limiting judgements" - so that a school could not be rated outstanding unless they scored top marks in teaching and learning.
"To be graded outstanding is very demanding. There have to be many good features and we should be recognising those achievements, not devaluing them," he said.
"We know that teaching and learning is at the heart of what we do, but it takes time for that to be outstanding across the board. The key issue is that a school is led in a way that makes it possible for a school to achieve."
Russell Hobby, general secretary of the National Association of Head Teachers said: "Another morale booster for the profession from the secretary of state.
"Michael Gove's sudden doubts about the validity of outstanding ratings are disturbing given the speed with which the government has rushed to exempt outstanding schools from inspection and grant them Academy status."