The BPI has slammed ACS:Law for the way it has chased a number of Brits suspected of illegally downloading.

Which? revealed this week that law firms had been sending out letters on behalf of copyright holders to UK web users, claiming they have participated in illegal file-sharing and ordering them to pay £500 and sign a legal undertaking agreeing not to re-offend in the future.

Adam Liversage from the BPI, told the BBC: "We don't favour the approach taken by ACS:Law to tackle illegal file-sharing".

"Our view is that legal action is best reserved for the most persistent or serious offenders - rather than widely used as a first response."

The letters are being issued even though the Digital Economy Bill, which sets out measures by the government to tackle internet piracy, has not come into force in the UK yet.

The measures suggest a 'three strikes' rule under which potential offenders will receive warning letters and emails designed to educate them on their wrong-doing. Should they continue to offend, web users will then face disconnection from the web.

However, the letters that have been received so far appear to be less about educating web users and more about issuing a penalty.

The BPI also revealed it will not employ the same approach as ACS: Law when internet piracy measures come into force.

Meanwhile, Michael Coyle - a lawyer representing around 100 Brits that have received letters from law firm Lawdit - told the BBC he was concerned about the number of web users accused of illegally file-sharing and called for the Information Commissioner to investigate the matter.

"I suspect that many hundreds of people have been innocently accused of copyright infringement and the accusations continue without any organisation being prepared to intervene," he said.

"Ideally the Information Commissioner ought to intervene and seek to prevent the courts releasing the personal data of thousands of individuals."