Keith Weller of the Qualifications and Curriculum Authority: "It is a bit worrying"

The proportion of papers receiving grades A* to G has dropped from 98.5% last year to 97.7%, only the second such fall in the decade since the qualification was introduced.

But there has been a slight increase in the proportion of top grade passes, with 54.7% of papers attracting A* to C grades - up 0.3 percentage points on 1997.

This has prompted fears that schools are focusing resources on those pupils most likely to get A* to C grades, at the expense of less able children.

In the key subjects, the top grade pass rate increased in English and the sciences but fell slightly in maths.

The end of the anxious wait for GCSE results

Around half a million children in England and Wales have collected their results, but the pass rate figures also include Northern Ireland, where most children received their results nine days ago.

Baroness Blackstone: "These are very good GCSE results"

The Education Minister Baroness Blackstone congratulated candidates on the results.

"Students this year have followed a new generation of GCSE syllabuses which placed new demands on them," she said. "They and their teachers have clearly adjusted successfully."

Total GCSE subject entries fell slightly to 5,353,095.

The proportion of grades at A* to C in English was 56.5% (up from 56.0% in 1997), in mathematics it was 46.9% (down from 47.3%), and in the sciences it was 53.2% (up from 52.9%).

Baroness Blackstone said: "The study of English is at the heart of the school curriculum, so I am pleased to see rising attainment in this subject at GCSE.

Baroness Blackstone: "We are already taking action to deal with the poor levels of numeracy"

"I am pleased too that entries and attainment have held up well in science, but I am disappointed that the proportion of higher grades in the equally important subject of mathematics has declined slightly.

"This highlights the need for a greater focus on the teaching and learning of numerical and mathematical skills in schools."

The UK's largest teachers' union, the National Union of Teachers, says the results expose the fallacy of claims that exams are getting easier.

Its General Secretary, Doug McAvoy, said: "Proponents of grade inflation have failed miserably to make their case."

The Shadow Schools Minister, Theresa May, said the previous government had improved educational standards but she was concerned by the overall fall in the pass rate this year.

"With this Labour government insisting on interfering in all aspects of classroom life, I hope this is not evidence of the government squandering our golden education legacy in the way they are squandering our golden economic legacy."