Prof Andrew Pollard said that a reform of core subjects for five- to 11-year-olds would promote a target-driven culture and fail to provide pupils with a “broad and balanced” education.
The comments are being seen as an embarrassing blow to the Coalition which named Prof Pollard on a four-strong panel set-up last year to review the National Curriculum.
It comes just days after ministers outlined new study programmes in the core subjects of English, maths, science and foreign languages.
In a radical departure from the existing curriculum, the document sets out the basic knowledge that all pupils should master in each year of primary education.
This includes an emphasis on mental arithmetic, times tables, fractions and decimals in mathematics and a more rigorous focus on spelling, grammar and fluent reading in English.
Ministers also proposed to introduce more experimentation in science lessons and ensure that all children learn a foreign language from the age of seven.
Schools will be expected to ensure that all children grasp the curriculum content before moving on to the next year.
But Prof Pollard, an expert in classroom teaching from the Institute of Education, part of the University of London, said that the approach was “fatally flawed without parallel consideration” of the needs of individual pupils.
Writing on his blog, he said teachers had to take account of the needs of each child to provide a broad curriculum, adding: “However, on the basis of the new National Curriculum proposals, they are to be faced by extremely detailed year-on-year specifications in mathematics, science and most of English. This is to be complemented by punitive inspection arrangements and tough new tests at 11.
“The constraining effects on the primary curriculum as a whole are likely to be profound and the preservation of breadth, balance and quality of experience will test even the most committed of teachers.”
The Coalition established the expert panel – headed by Tim Oates, from the Cambridge Assessment exam board – in January 2011 to investigate methods used by top-performing education systems from around the world.
It produced a report in December last year outlining the tactics used in countries such as Singapore, Hong Kong, Poland and parts of North America.
But Prof Pollard said it was "far from clear that these sources have influenced the proposals" published this week.
He claimed that three of the four committee members quit after the publication of the December report because they could not back the “detailed year-on-year” syllabus model favoured by the Government. It left Mr Oates to develop the curriculum alongside Department for Education officials, he said.
“Expectations should be high, but if targets are unreasonable they will simply generate a widespread sense of failure,” he said. “Tidying up 'knowledge' is a desk exercise, but in the real world of classrooms the range of pupil needs is enormous. These cannot be wished away.”
Responding to the claims, Mr Oates said said Prof Pollard's concerns were "misplaced".
“The principles agreed with the expert pPanel, including Andrew, at the start of the review remain in place," he said. "There is greater demand and detail in the content of these key subjects and there is greater freedom for teachers in how they teach it.
“Publishing content year by year is not some rigid straitjacket. There remains flexibility for schools in the scheduling of content. The draft programmes of study are drawn from a rigorous research base, both domestically and internationally."
But the comments were seized upon by Labour, which branded the comments "highly embarrassing" to the Government.
Stephen Twigg, the Shadow Education Secretary, said: "It now seems that after commissioning an in-depth review, the Government is ignoring many of its recommendations in favour of its own prejudice.
"The Government should put evidence ahead of dogma when it comes to education. The curriculum mustn't be prey to political ideology."