There is "little or no evidence" that teaching phonics boosts literacy skills, according to an academic specialising in language and memory.
Professor Jeffrey Bowers, from the University of Bristol, has said that despite "widespread consensus in the research community" that the reading method is preferable to meaning-based approaches, there is a lack of "empirical evidence" to suggest that it leads to better outcomes.
Last year, school standards minister Nick Gibb declared victory in the "phonics wars" by saying that the "debate is over" about the best way to teach reading.
Nick Gibb: The phonics wars are 'over'
Mr Gibb said that, while there were still commentators "desperately clinging to romantic notions" about reading, it was time for the debate to move on to "which phonics programmes are most effective".
Does phonics make a difference?
But new analysis of the evidence by the university lecturer directly contradicts Mr Gibb's claims.
In an article for Educational Psychology Review, Mr Bowers writes: "The 'reading wars' that pitted systematic phonics against whole language are best characterised as a draw.
"The conclusion should not be that we should be satisfied with either systematic phonics or whole language, but rather teachers and researchers should consider alternative methods of reading instruction."
Mr Bowers conducted a "detailed and exhaustive review" of all meta-analyses (studies that assess existing research) into the efficacy of teaching systematic phonics. He also assessed the impact of making phonics compulsory in English state schools.
As part of his analysis, Mr Bowers refers to an independent report by Sir Jim Rose, published in 2006, which led to the legal requirement to teach synthetic systematic phonics in state schools, effective from 2007 onwards.
Mr Bowers says the report's conclusion – that "the case for systematic phonic work is overwhelming" – is "unwarranted", as the research "provides little or no evidence that systematic phonics is better than standard alternative methods used in schools".
He adds: "There can be few areas in psychology in which the research community so consistently reaches a conclusion that is so at odds with available evidence."
Mr Bowers refers to the rollout of phonics in English schools as a "massive naturalistic experiment", adding: "It is widely claimed that the experiment has been a success with systematic phonics improving literacy. But once again, a careful look into the findings shows that the data do not support this conclusion."
He adds: "In summary, despite the widespread claim that children are reading better in England since the mandatory inclusion of systematic phonics in state schools in 2007 and the introduction of the PSC [phonics screening check] in 2012, there is little or no evidence to support this conclusion.
"Indeed, the only noticeable change in performance is on the PSC itself, with no discernable effects on reading more generally."
A Department for Education spokesperson said: “Our focus on phonics in primary schools is helping more pupils open up to the joys of reading.
“In 2016, England achieved its highest ever score in reading, moving from joint 10th to joint 8th in the Progress in International Reading Literacy Study (PIRLS) rankings.
"This follows a greater focus on reading in the primary curriculum, and a particular focus on phonics.”