He was speaking as the University of Cambridge began a poster campaign designed to break down the elitist stereotypes which discourage applications.

"Many state school pupils getting three As at A level are not applying for Oxford and Cambridge," Mr Blunkett said.

"There can be no question of diluting standards of entry, but any pupil who gains the required qualifications should be encouraged to apply, and it should be made easy for them to do so."

Mr Blunkett welcomed the Cambridge campaign.

"I hope that more state schools will take the opportunity to find out more about the university, its entrance requirements and applications procedures, as I would like to see many more of them sending their most able students there."

Oxford and Cambridge universities are concerned at their lack of progress in repeated attempts to attract more state-educated students.

At Cambridge, only 47% of last year's intake of students came from the state sector, although 65% of state school students had A level results good enough to apply. Just 20% of the university's students had attended comprehensives.

By contrast, 45% of Cambridge students came from fee-paying private schools, which represent just 7% of the total school population.

Admissions tutors believe too many state school teachers are advising their ablest pupils that they will feel more at home in "red-brick" universities, and that Oxford and Cambridge are missing out as a result.

Attitude

Cambridge's poster campaign is aimed directly at state school sixth formers, over the heads of their teachers. Posters are being sent to all secondary schools, sixth form colleges and further education colleges in the UK, carrying the message: "Put yourself in the picture".

They show 14 students from state schools currently attending the university.

One of them is Mark Hypolite, who went to St Augustine's Comprehensive, in Kilburn, north west London.

"Some people think Cambridge is way above them," he said. "That's an attitude that comes from teachers and friends. I thought I was good enough to apply, and I did.

"I appeared in the poster because I wanted to show other state school students that Cambridge is as much for them as it is for me."