English teachers are concerned that the committee overseeing the national curriculum review could be biased in favour of synthetic phonics and includes a member with a business interest in promoting the reading method.
The National Association for the Teaching of English (NATE) is unhappy that synthetic phonics guru Ruth Miskin - whose company sells training courses to schools - is the only primary literacy expert on the Government-appointed advisory committee.
Its unease is compounded by the fact the only two serving primary heads on the committee are self-proclaimed users of Ms Miskin's synthetic phonics reading scheme - Read Write Inc.
Ms Miskin and the Department for Education deny any conflict of interest, saying the review will not be recommending teaching materials or schemes of work.
But David Gibbons, vice chair of NATE's primary committee, said: "The review may not suggest specific schemes, but if Ruth Miskin has been a key player in developing a new national curriculum then her business could benefit by association.
"The real concern for us is that she represents a particular point of view and we do see this as a potential conflict of interest.
"We are concerned that Read Write Inc could be rolled out as a solution through the national curriculum. She has obviously got a business interest in that and synthetic phonics in general."
"It is about having a plurality of methods - we don't deny there is a place for synthetic phonics but you do need to understand the difference between word recognition and reading."
The association has noted that a recent Ofsted report reporting the use of Read Write Inc in seven schools has been used to promote Ms Miskin's business.
The Read Write Inc website is now highlighting Ms Miskin's appointment to the national curriculum review advisory committee.
It also features another of the 14-strong committee's members - Shahed Ahmed - on its front page.
"Every child deserves the best," the quote from Mr Ahmed, head of Elmhurst Primary, Newham, east London, reads. "Read Write Inc has been instrumental in our quest that 'no child can slip through the net'." He declined to comment on NATE's concerns.
The association found that the school where John Martin, the other serving primary head on the advisory committee, is head has also been used to promote synthetic phonics.
A Conservative party press release during last year's general election campaign said Nick Gibb, now schools minister, had visited Castle Hill Junior School, Basingstoke, to "hear from headteacher John Martin how focusing on synthetic phonics has meant excellent reading results".
Mr Martin told The TES his school used Read Write Inc and a "variety of approaches including synthetic phonics".
"We select what we feel is appropriate for an individual cohort or an individual child. Synthetic phonics is a strong element but there are other approaches."
Asked for examples of alternatives to synthetic phonics used by his school, Mr Martin named two schemes that concerned writing rather than reading.
Ms Miskin said: "I was very pleased to be invited to take part in the review. I do not see there is a conflict of interest as the review will not be recommending teaching programmes or schemes of work."
A DfE spokesman said: "The review is going to be based on an exhaustive and hard-headed analysis of international and national research. We've appointed a wide range of experts to advise us - and are delighted to have a leading authority like Ruth Miskin working with us."