The proportion of papers resulting in an A* to C grades has risen by 0.9 percentage points to a record level of 56.6 per cent, prompting accusations that schools are focusing on C and D grade candidates whose results could boost their league-table positions.

Yet the proportion of ungraded papers rose very slightly this year from 2.0 per cent last year to 2.1 per cent this summer - a total of about 7,600 more failures - based on a comparison of provisional figures issued each August.

This is the third fall in the overall A* to G pass rate in the past 10 years, according to records kept by the Joint Council for General Qualifications which publishes results. In 1998 the failure rate jumped from 1.5 per cent to 2.3 per cent.

One possible explanation for the increase in ungraded entries is that schools are encouraging weaker pupils to attempt GCSEs, which they would not have taken previously, or entering them for more subjects.

The number of 16-year-olds eligible to sit the exams was up by 2 per cent on last year to around 583,000, but total GCSE entries leapt by 5.4 per cent.

John Dunford, general secretary of the Secondary Heads Association, said:

“Schools get no credit for turning a B into an A grade, or an F into an E. The Government needs to recognise all achievement.”

DavidHart, general secretary of the National Association of Head Teachers, said: “The rise this year is good news but the tail of underachievement will not be shortened significantly without substantial investment in the early years of secondary education.”

Meanwhile, increasing numbers of students sat half GCSEs to broaden their studies, according to provisional GCSE results released this week.

Entries rose by 8 per cent with almost half of all short-course entrants sitting the religious education exam, allowing them to gain a qualification in a compulsory subject in half the study time of a normal GCSE.

The short course GCSE is also the minimum requirement for design and technology and modern foreign languages but, surprisingly, almost all of these courses saw a drop in entries this year.

Job-related courses which have been dubbed “vocational GCSEs” enjoyed a 41 per cent rise in popularity this year, with 32,350 students registering for part one General National Vocational Qualifications. The courses - equivalent to two GCSEs - provide an alternative programmefor pupils who would not thrive on an academic course. They may provide a template for new vocational GCSEs which start in 2002.

Meanwhile the GCSE gender gap increased very slightly this year - 61.1 per cent of female entries gained at least a C grade compared to 51.9 per cent for boys.

The gap was widest for art with girls showing an advantage of 20 percentage points in the proportion getting A* to C grades.