An influential group of headteachers has lobbied Damian Hinds to question the need for a new Ofsted inspection framework.
Ofsted is planning to focus more on school curriculum and less on exam results when it launches a new inspection regime next year.
Now the Headteachers’ Roundtable group has written an open letter to the education secretary warning that the changes will increase teachers’ workload.
And they have claimed that inspectors are already starting to focus more on school curriculum under the current framework and questioned whether the inspectorate needs to launch a new one.
Ofsted has said that changing its approach within the existing framework would lack transparency and would increase workload by "driving schools into the hands of consultants who claim to know ‘what Ofsted wants’".
The Headteachers' Roundtable however claim that the new framework will also mean increased workload.
In a letter to Mr Hinds, they said: “We will await the publication of Ofsted’s full framework in January 2019 but remain unconvinced that a new framework is required.
"The inevitable increased workload associated with its implementation is known to those of us who have been leading schools for many years; we have been here before.
“Anecdotal evidence suggests the current framework is already being morphed by inspectors to prioritise the curriculum.
"It may well be that changing the emphasis within the current framework is a more appropriate way forward pending a fundamental review of the Department for Education’s school improvement theory of change.”
Ofsted’s plans for a new inspection regime will see the judgements on both pupils’ outcomes and teaching and learning make way for one grade on the quality of education a school provides.
The changes have been described as a “crackdown on exam factory” schools and an attempt to recognise the education a school provides rather than just the grades they achieve.
Earlier this year Ofsted’s chief inspector Amanda Spielman said the plans were a “warning shot across the bows" of schools getting results the wrong way.
She also said that the new inspection framework being introduced next year will reduce workload.
However, Mr Hinds has voiced concerns that their changes could increase work in schools.
This has also been raised by the NAHT headteachers' union, which has called on Ofsted to put its plans on hold amid fears over workload and the amount of time it has to implement such a major change.
An Ofsted spokesman said: "Changing the way we inspect by stealth, rather than through a new framework, would not only lack transparency, it would also increase workload by driving schools into the hands of consultants who claim to know ‘what Ofsted wants’.
"In contrast, the new framework will be clear about what inspectors will look at and why. What’s more THE focus on the curriculum will help to tackle excessive workload, treating teachers as professionals in their discipline rather than as data managers."
The Department for Education has been approached for comment.
Earlier this month the inspectorate produced 24 slides which set outs its vision for a new inspection framework.