One of the top scanning systems, Turnitin, is being employed in a study for the Joint Council for Qualifications, the umbrella body for Britain's examination boards. From next year, Northumbria Learning will be scanning coursework examined by one of the main boards, Edexcel.

The move to tackle the use of online databanks - providing pre-prepared answers and essays - follows a report yesterday by the Qualifications and Curriculum Authority which warned that exam boards are failing to catch cheats.

Most of the websites could not be contacted or declined to respond yesterday. But Matthew Wilson, managing director of Essaywriter.co.uk, said yesterday: "Copying essays has been going on since time immemorial. In the middle ages students at Oxford and Cambridge copied from each other."

He said prices varied from £4,674 for an MA dissertation down to, for example, £128 for a 2,000-word history essay. Much of his business comes from overseas students.

Selling answers has spread rapidly across the internet. "If you intend to copy the work," advised one offer on eBay yesterday for material from an Information & Communication Technology AS-level course, "remember to change my names, dates and IDs to yours."

Scanning technologies have been used for some time in universities. But they have not been used to check schoolwork until now.

The systems take a computer document and crosscheck it against other files to spot similarities between them. Most work like souped-up internet search engines, comparing the text of a suspect document against a large database of material to see what matches.

Turnitin already claims more than 7 million subscribers worldwide, and compares submissions with a database of books and journals as well as more than 4.5bn web pages. It also checks them against its own library of more than 10m previously submitted papers.

Courseworkbank, which claims to be the largest UK database of free student written essays, lists A-level and GCSE papers by topic.

"Everything is made available completely free of charge for our users," it states on its website. "Please consider contributing your course work and essays in return."

While universities deal with relatively small numbers of students, examination boards deal with many more pupils each academic year. Monitoring plagiarism will become more difficult when electronic submissions will be made mandatory for all secondary level coursework by 2009.