Conflicting messages from ministers telling schools they should compete and collaborate are undermining improvements to education, a former senior adviser to the Prime Minister and the Education Secretary said.
Robert Hill, who was a private secretary to Tony Blair and later Charles Clarke's special adviser when he was Education Secretary, makes the criticism in a book being published next week by the Association for School and College Leaders.
"The Government's mixed messages on competition and collaboration between schools are undermining attempts to deliver sustainable improvement at a local level," he writes in Leadership that Lasts. There is a conflict between encouraging schools to outperform each other in league tables and attempts to make schools cooperate, he said.
He said the Government's education white paper claims "with confidence but without evidence" that new self-governing trust schools will improve collaboration.
"Given that they are competing for parents and pupils and they will be judged by their results, it is hard to see what the drivers for collaboration will be.
"The risk is that at best pragmatic fixes will emerge and at worst collaboration will be token and ineffective," he writes.
Mr Hill's comments come a week after Sir Michael Bichard, the former permanent secretary at the Department for Education and Skills, said that making schools more competitive could lead to greater numbers of pupils dropping out.
Meanwhile, the shift towards a market-based education system has been praised by Sir Michael Barber, who was head of the Department for Education and Employment's Standards and Effectiveness Unit from 1997 to 2001 and the Prime Minister's delivery unit from 2001 to 2005.
He told the American website Education Sector that he began to appreciate Conservative education reforms when he was a leading National Union of Teachers official.
"I think one of the best things Blair did was design his education reform to build on the important Conservative reforms," he said.