Government plans to axe GCSEs in favour of a new exam could fail to help less able pupils and leave some subjects with discredited qualifications, a cross-party group of MPs has warned.
In a damning report, the Commons education select committee said that while significant improvements to GCSEs were needed, ministers had failed to prove their case for scrapping the qualification, and urged them to slow down the pace of reforms.
Labour leader Ed Miliband told ITV1's Daybreak the select committee's report was "part of a groundswell against Michael Gove's plan" because he is "squeezing creativity out of the curriculum".
He added: "Also he's not really focusing on those kids who maybe aren't going to go to university but need high quality vocational qualifications.
"That is what I'm talking about today. If you are a 14-year-old today you might know that you're going to do A-levels and then go to university, but what if you're going a different path?
"What if you're not academic? I think you or I would probably find it hard to say what young people will be doing at 18.
"What we want is a gold standard vocational qualification so that people know - young people, parents know - that there's a good qualification that they can do and it's going to be respected by employers.
"And also make sure the apprenticeships are there for them when they leave school or college."
The report from the select committee raised serious concerns that the pace and scale of the reforms could jeopardise the quality of the new exams and that there was a "lack of coherence" about the government's approach to reforming the curriculum, qualifications and the school accountability system.
Education Secretary Michael Gove announced plans last year to axe GCSEs in favour of new English Baccalaureate Certificates (EBCs) in English, maths and science.
The qualifications will be first taught in September 2015, with students sitting the first exams in 2015.
EBCs in history, geography and languages will follow at a later date, and GCSEs are set to remain for other subjects.
But in its report on the proposals, published today, the select committee said it had a number of concerns about the reforms.
The government has yet to make the case that GCSEs are so discredited that a new exam is needed, and it should publish the full results of its consultation into the reforms to justify why the brand is so damaged it is beyond repair, the committee said.
And it warned that the reforms could have a negative impact on subjects that would remain GCSEs.
"We are very concerned about the potential impact of the EBCs on subjects outside the English Baccalaureate, which will be left with 'discredited' GCSE qualifications for some time," the report said.
"We question the extent to which it is possible to 'upgrade' some subjects without implicitly 'downgrading' others."
Official figures show that in 2011/12, 41.4% of teenagers did not get five GCSEs, including English and maths, at grades A*-C, the report said.
It suggested that the government should focus on improving the achievement of the "significant minority" that do not achieve five good GCSEs.
"While it is right to raise young people's expectations and aspirations, we fail to see how raising the bar will automatically result in more young people achieving higher standards," the report said.
"Furthermore, we have serious concerns about how well the proposed reforms will serve the 40% plus of pupils who do not achieve the Government's current floor standard."
The committee also calls on ministers to rethink plans to introduce a Statement of Achievement for lower-attaining pupils.
Committee Chair Graham Stuart said: "We do not see how this will be any more useful to young people than a low grade GCSE or alternative qualification.
"It may even become a badge of failure."
The committee criticises the Government for pressing ahead with GCSE reforms before publishing the findings of a review of the national curriculum, and its plans to reform the school accountability system.
Stuart, Conservative MP for Beverley and Holderness, said: "No sensible reform of assessment can take place without clarity as to what is to be taught. Coherence is not achieved by accident but by design."
The select committee is the latest group to raise concerns about the Government's GCSE reforms.
The exams regulator, Ofqual, has previously raised concerns about the timetable for reform.
In a letter sent in November, chief regulator Glenys Stacey also warned Mr Gove that his aims for the new qualification may not be "realistically achievable".
In its report, the select committee said there is wide-ranging opposition from some quarters to parts of the Government's proposals, adding: "Changes of this magnitude are best achieved with as wide support as possible from across the education system, the wider economy, young people and their parents and, not least, the political spectrum."
A Department for Education spokeswoman said: "We have been clear that the secondary education system is in desperate need of a thorough overhaul - an objective with which the committee agrees. That is why we are making major changes to ensure we have world class exams that raise standards."
Shadow education secretary Stephen Twigg said: "Michael Gove has become the enemy of ambition. This damning report supports Labour's warning that the Tory-led Government's changes will do nothing to improve standards, especially for low-attaining pupils.
"This risks leaving schoolchildren with a badge of failure. He needs to go back to the drawing board."
Christine Blower, general secretary of the National Union of Teachers, said: "Michael Gove and the Coalition Government's position on examination reform is now surely untenable. The Education Secretary is totally isolated in his view that the English Baccalaureate Certificates are a suitable measure to replace GCSEs."
The select committee's report comes as the Government announced that computer science is to be included in its English Baccalaureate.
Currently pupils achieve the Ebacc if they score at least a C at GCSE in English, maths, two sciences, history or geography and a language.
Computer science is to be added to the list of science options, alongside biology, chemistry and physics.
Youngsters who sit any three of the four, and get at least a C in two of them, will fulfil the science part of the Ebacc.
The Department for Education said that the change has been made because computer science is important for education and the economy.
Russell Hobby, general secretary of the National Association of Head Teachers (NAHT), said: "The Government's proposals not only risk chaos in terms of implementation, they relegate non-EBC subjects to second-class status.
"Of course we need English, maths, science, languages and history, but we need art, drama, design, sport and technology too.
"The lack of a clear vision for vocational education within the EBC scheme is also glaring. Too many young people - the students who most need our attention - are neglected by these proposals."