The centre has reported more than 10 similar cases in the past year and students involved were warned but not prosecuted. The latest case has led to the first arrest.

With the help of internet service providers, customs officers tracked down the student and arrested him on Tuesday at Kowloon Bay MTR station when he was trying to sell the pirated discs to a customs officer posing as a buyer.

The student was then taken back to his home in Mongkok, where officers found 21 compact discs containing illegally recorded lectures, a computer containing the same pirated copies and a recording pen. The lectures were from the private tutorial school which the student had attended since June last year. They included lessons by popular lecturers such as Kevin Ko in economics and Derek Liu in English.

Customs officers suspected that the student first used the recording pen to record lectures during lessons, then inputted the audio files to his computer to burn the lectures on CDs as mp3 files.

The student allegedly posted advertisements on the internet with false personal information and sold the discs for about $250 to $300 per set. One ad, selling the set for Form Seven Economics, said it included two discs containing recordings of 40 lectures of 75 minutes each. Each school course cost about $420 per month.

Senior Inspector Jimmy Tam Yat-keung, head of the customs anti-piracy team, believed the student had sold fewer than 10 sets.

He said the tutorial format of the school provided the opportunity for the student to record the lessons. Top lecturers usually did not attend the classes in person. Instead, a DVD recording of their lectures was shown in class.

The student has been released on a $2,000 bail as investigations continue.

Mr Tam said there was an upward trend in trading copyright violating items through internet auction sites. Eight cases were cracked last year but there were already six cases detected in the first half of this year. But he said his department had the capability to fight such crime.

Mr Tam urged teenagers not to use computers to commit crimes. Anyone found possessing items for trading purposes faces a maximum penalty of four-year jail and $50,000 fine per item where copyright has been violated.

Folia Yiu Tung-yan, course and marketing manager at King's Glory Education Centre, said the school did not know by how much business had been affected. 'But these discs were massively produced and cheaply sold, it is certain ... our business is suffering,' she said.