Trade unions have criticised ministers for the delay in producing "useless" league tables following last year's A Level results fiasco.

The data, delayed after the marking crisis, reveals a marginal increase in performance across the board. The average point score for each exam entry was 73 points in 2001 and 76 points last year using a new assessment system.

David Hart of the National Association of Head Teachers said ministers should have scrapped plans to publish the results. "The A Level marking fiasco should have led to their abandonment," he said.

"As it is, they make little or no contribution to the sum total of knowledge about the performance of schools.

"Insofar as they tell the public anything, they confirm that high performing comprehensives achieve results as good as any in the independent sector or, indeed, better if you take into account their non-selective intake."

But school standards minister David Miliband insisted the exercise was justified and congratulated students and teachers on improved performance.

"Many students have obtained high-quality qualifications in more subjects, raising their overall level of achievement. There is now more flexibility in post-16 education, which promotes rigorous study across a wide range of subjects," he said.

"The reforms to the post 16 curriculum mean that students are able to track their progress as they study, getting more support from teachers in areas of weakness. The new modular assessment means they can be motivated by their success as they go along.

"In addition, they can decide the subjects they will study at A Level after their first year of AS Levels so they can make right choices for their future.

"We are determined to promote high standards across a wide range of subjects, maintaining the reputation of A Levels whilst broadening the scope of study.

"The combination of academic and vocational learning now available is boosting students' skills and helping them develop their potential and achieve success."