The Education Select Committee’s investigation of public expenditure in education also condemned a lack of transparency and cautioned that taxpayers might not wish to pay for state schools in future unless ministers can demonstrate that the resources are being used wisely.

This lack of information, the Labour-dominated committee said, would not only be bad for taxpayers but could also “undermine the electorate’s willingness to fund public services”.

But the MPs reserved their harshest criticism for the Chancellor’s commitment in this year’s Budget to raise the level of funding per pupil in state schools from £5,000 to £8,000, the average spending per head in independent schools.

Although Mr Brown was widely praised for his pledge in March, The Times quickly established from Treasury sources that this was only an aspiration.

After questioning Alan Johnson, the Education Secretary, and David Bell, his top official, the MPs said that it remained to be seen how the aspiration would be backed up with funding.

The select committee said that it was hard to judge when this pledge could ever be met. “Without a timescale it is hard to be certain when the target would be met,” the report stated. “The debate on what is the appropriate level of per-pupil funding is important. Future policy announcements should have a more substantial basis.”

The Institute for Fiscal Studies has since estimated that it would cost £17 billion to close the gap between the public and private sectors and that this would not be achieved until at least 2014.

The MPs also warned that there was no way to demonstrate whether the Government’s increased funding for schools had been effective and had succeeded in providing better education or more highly qualified students.

Since Labour came into office, public spending on education has risen from £21.43 billion in 1997-08 to £34.35 billion in 2005-06.

But recent figures from the Office for National Statistics showed that only 41 per cent of pupils achieved five grades A* to C in English, maths and science and only 26 per cent of pupils got good grades in English, maths, science and a language — a fall of 4 percentage points from 2002.

Last night a spokesman said that the Government had invested record amounts in education, and “as a result we are seeing more schools with more teachers and better results”.

“Investment in education is a key priority for the Government. As the Chancellor said in his Budget speech, the Government’s long-term aim is that we raise average investment per pupil to today’s private school level. That position remains unchanged.”

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