The overall pass rate rose by 1.8 per cent - broadly in line with recent years. It appears to confound speculation that the recent introduction of modular courses has made the A-level easier.

The number of students gaining A grades also increased, but only by 0. 4 per cent, a slower rate of increase than in previous years.

Entry levels for key subjects such as English and mathematics have held up well. Numbers taking physics and chemistry have, however, continued to decline - a further concern for universities and manufacturing industry.

The physics entry fell by 5.7 per cent, chemistry by 4.3 per cent. The trend was immediately criticised by the Labour party, whose spokesman Bryan Davies said that the proportion taking maths and science had fallen from 30 per cent in 1984 to 17 per cent in 1995.

There were also continuing declines in economics (down by 7.6 per cent) and classical subjects (5.5 per cent). Entry rates for biology, French, German, history and English remained the same.

The improved pass rate was welcomed by exam boards and opposition parties. David Hart, general secretary of the National Association of Head Teachers, said claims of falling standards were “poppycock”.

Controversy had been generated before publication of the results, with complaints from some commentators that modular courses in English, maths and science - where the final exam accounts for only 30 per cent of the marks - conferred an unfair advantage.

Former education minister Sir Rhodes Boyson said this week that modular A-levels were “not worth the paper they are written on”. This was the first year that such courses - one in five of total entries - accounted for more than a small percentage of students.

The only research to have been undertaken on modular courses has suggested that candidates may achieve one grade better on average than they would have done under a traditional “linear” course.

Several motivational factors are thought to contribute: modules present short-term objectives and keep candidates working more consistently; students can re-take modules much more easily than they could re-sit an entire A-level.

While the pass rate for modular courses was slightly higher, fewer candidates achieved grade A.

The explanations are as yet speculative. However, it seems possible that a wider ability range has been encouraged to take modular courses with their promise of step-wise progression. Furthermore, A-grade performances are harder to sustain over two years of modules than in a few adrenalin-fuelled hours in a traditional exam.

In an attempt to head off criticism of modular A-levels, the Government has accepted a recommendation from the chair of the School Curriculum and Assessment Authority, Sir Ron Dearing, and has agreed to consider limiting the number of times that a candidate can re-take any one module.

It has also set up an inquiry into A-level standards, the results of which are expected in the autumn.

Modular courses may explain another phenomenon; the fact that physics and chemistry entries rose for the AS-level despite falling for the A-level. At this stage it seems plausible that modular candidates who were unlikely to reach a full A-level pass cut their losses and concentrated on an AS-level instead.

Kathleen Tattershall, chief executive of the Northern Examinations and Assessment Board and this year’s convener of the joint GCE boards, said that modular courses have helped to reduce the risk of outright failure in difficult courses like maths and science.

George Turnbull, spokesman for the Associated Examining Board, attacked the annual complaints about falling standards. “If that’s the best they can do, then really . . .” said Mr Turnbull. “Sir Rhodes Boyson has no idea of what’s happening with these examinations.”