China's top court stepped up the fight against intellectual piracy by lowering the threshold for criminal manufacture or sale of counterfeit intellectual property products.

A new judicial interpretation issued by the Supreme People's Court on Thursday states that anyone who manufactures 500 or more counterfeit copies (discs) of computer software, music, movies, TV series and other audio-video products faces a prison term of up to three years.

The new rules also widen the definition of a "serious IPR offender" - anyone who produces more than 2,500 counterfeit copies can be thrown into jail for up to seven years.

The rules are effective immediately, the top court said. They replace the 2004 rules whose net only extended to infringers who produced 1,000 pirated discs and which defined "serious offenders" as those who produced over 5,000 copies.

Sources with the Supreme People's Court said they made the change in order to deal with "new problems" in the crackdown on piracy.

"The courts will extend the protection of intellectual property rights and play to the full their role in punishing infringers and preventing crimes," a court spokesman said.