Office for Standards in Education inspectors found that one in five awards given to 180 sixth-formers, supposed to be equivalent to A-level, did not reach the correct standard. Of the 100 portfolios given "merit or distinction" grades, a sixth had been marked too generously. Inspectors found "significant inadequacies in assessment and grading" in one in three schools.
Ofsted also found that three-quarters of the students had achieved more than would have been expected if they had taken A-levels. The best showed "maturity, commitment and a conscientious approach" and produced "mature work of impressive range and depth".
The Qualifications and Curriculum Authority is piloting tougher grading , but Ofsted emphasised that this will not help students gaining awards over the next three years. Until 1999, the QCA should introduce more rigorous external checks, says Ofsted.
This report mirrors others on the GNVQ published by Ofsted since 1993. The qualification is taken by more than 200,000 students in 2,000 schools and colleges.
* There is no clear link between Britain's poor economic performance and low levels of education, according to the Government's most-trusted think tank.
Labour ministers have consistently argued that by raising standards of basic skills, they are paving the way to future prosperity.
The Institute for Public Policy Research this week described such assumptions as "ill-conceived".
In a paper entitled The Tyranny of League Tables, Peter Robinson, the IPPR's chief economist, attacked the Government's reliance on tests and targets. He warned against turning teachers into scapegoats for national failings.
"The evidence linking mathematics attainment and the level of, or growth rate in, per capita GNP is very weak," he said.