Tony Blair should have waited for evidence that existing academies raise standards before pushing ahead with a massive expansion, the Government was told this week.
Education Secretary Charles Clarke admitted to MPs that it is too early to say whether the first 12 academies have succeeded but said he hoped they would end decades of poor performance in deprived areas.
Plans to raise the number of academies - state-funded schools free of local-authority control - to 200 are at the heart of the Government's five-year education plan unveiled yesterday.
But, at an Education Select Committee hearing, David Chaytor, Labour MP for Bury North, asked Mr Clarke whether a government committed to "evidence-based policy" should have waited for an evaluation of academies due to be published later this year.
Mr Clarke said: "You might argue that. The problem with any policy announcement is that you have a set date and I do not think we could postpone that." He admitted none of the 12 academies had been open long enough to do a systematic assessment. The policy would be reviewed in the light of future evidence, he promised.
Barry Sheerman, committee chair, described the Government's strategy as "risky".
The plan is also expected to make it easier for secondary schools to bid for foundation status. It contained a pledge to let successful schools expand.
But Steve Sinnott, general secretary of the National Union of Teachers, has deep concern about more schools opting out of council services by becoming foundation schools or academies. "We think there are real dangers here - this is a major undermining of the comprehensive, locally-adminstered system of education," he said.
Mr Sinnott also said the five-year plan seemed to undermine the Children Bill, which aims to build closer links between education and other local public services to improve child protection.
Mr Clarke also admitted that successful schools that need extra buildings to expand would have to persuade their education authority that they deserved funding more than schools needing repairs.
Speaking during Prime Minister's question time, Tory leader Michael Howard said that just four of the country's 21,000 schools had so far taken up their existing right to expand.
The Professional Association of Teachers said there appeared to "very little new" in the plans. "Schools already have flexibility in pay and conditions - for example, to move teachers up the pay spine and use management allowances," said Jean Gemmel, general secretary.
David Hart, general secretary of the National Association of Head Teachers, said extra autonomy for schools was "a step in the right direction" and that the new-style foundation status should be available to primary and special schools as well. He said the extra spending planned for under-fives would probably have the greatest long-term impact.
The Government's plans to establish "rigorous teaching and learning reviews" also received a mixed reaction from unions.
Gwen Evans, deputy general secretary of the Association of Teachers and Lecturers, said staff would like support to improve their skills. But she said: "There is no doubt that this is accountability with teeth," she said.
The National Secular Society, called the expansion of academies "an act of educational vandalism". It fears academies will give religious groups greater influence.
The Socialist Education Association said Mr Blair had shown contempt for Labour's National Policy forum which meets this month to discuss the party's next manifesto.