The prime minister has defended school standards after a Commons committee report found one million children were not getting a good education. 

Tony Blair said the report, published by the public accounts committee on Tuesday, had changed the definition of what is a failing school.

The committee's definition included "a whole series of schools which aren't failing in the traditional definition but simply not performing as well as they should be," Blair said.

The committee warned that nearly one million children are receiving a poor standard of education.

After examining evidence from the Department for Education and Skills and the schools watchdog Ofsted, it found that even though the number of 'poorly performing' schools has been falling, there are still around 1,500, that fall within this category.

Committee chairman Edward Leigh said the findings of the report were a "tragedy".

"The consequences in the long term for the pupils themselves and, more widely, for our society will be severe," he added.

But speaking at his monthly press conference in Downing Street, Blair insisted schools were improving.

The number of schools in special measures has declined by over a half, he said.

And the number of schools where under a quarter of the pupils are getting five good GCSEs has been capped to a sixth of what it was.

"In every single part of the system there are improvements," Blair added, although he acknowledged "we need to do far more".

Teaching unions also accused the Commons committee of "scaremongering" in its report.

The National Union of Teachers said the report was a "gross simplification of the reality of education in our schools".

General secretary Steve Sinnott said there may be several reasons why a school is experiencing difficulties, "but that certainly does not mean those schools are failing their children".

"This is an alarmist scare story, but parents should be reassured that their children are receiving high-quality education in the vast majority of the country’s schools," Sinnott added.

The committee of MPs said their findings had shown there needed to be better data available on standards in primary schools so it is easier to identify schools which are in decline earlier.

It also said investigations at schools which are underperforming, which Ofsted carry out, should be more thorough.

Ofsted should also do more to identify when head teachers are over-evaluating their school's performance, the report said.

It recommended more innovative approaches to recruiting into difficult teaching posts in schools, and more support to individual head teachers at local level.
 
And it suggested more school-to-school collaboration, and that schools be given financial management assistance to make the most of central resources.

Leigh said: "The signs of decline in a school need to be picked up early and effective remedies applied."

She said a good head teacher is central to a successful school.

"Good pupil discipline, staff morale and continuity in education all improve under competent leadership. Yet schools, especially in disadvantaged areas, are crying out for inspiring head teachers," Teather added.

"We need a clear business plan to ensure talented teachers can reach headship earlier in their careers."