The use of computers in Scottish schools has had no impact on exam results despite investment of £150m over the past five years, according to a new report.

Schools inspectors found that, despite the potential to transform learning, there was no evidence that the use of information technology had increased attainment in formal qualifications.

The report, ICT in Learning and Teaching, also highlighted concern over internet plagiarism, with teachers reporting greater numbers of pupils cutting and pasting material from the web directly into homework.

Inspectors concluded that for computers to transform learning, schools needed to have access to reliable and modern equipment with good training and technical support which would build teachers' confidence and skills.

Where schools were using computers well, it helped pupils build effective problem solving skills, encouraged independent learning as well as communication and teamworking and improved the opportunities for teachers to collaborate.

However, despite progress, "excellence exists only in isolated pockets," the report found.

"There has been a general improvement across all sectors, but the overall impact of the adoption of ICT in learning and teaching does not reflect its potential," the report said.

"Learners' use of ICT broadens and deepens their learning. However, inspectors found no evidence of increased attainment, in formal qualifications or against nationally defined levels, that could be directly attributed to the use of ICT in learning and teaching."

Last night, the Educational Institute of Scotland blamed the problems on a lack of proper training. "While pupils and teachers are becoming increasingly skilled, teachers are often not provided with adequate training when new resources are introduced," said a spokesman.

An executive spokeswoman said the report showed ICT was "steadily transforming" the nature of learning and teaching. "Inspectors found many examples of good practice where there was an increase in the depth and breadth of learning in subject areas and where learners' motivation and engagement improved," she said.

Eleanor Coner, of the Scottish Parent Teacher Council said: "Computing can work very well, but the good teacher is the most important thing."

However, Fiona Hyslop, SNP education spokeswoman, said it would take time for the full impact of technology to be felt. "It has got huge potential, but its impact depends on teachers and therefore investment in training is as important as the equipment and programmes."