Seven people who were part of a group that was providing set-top box service were indicted Wednesday for illegally transmitting audio-visual content to their customers, the Taichung District Prosecutors Office said.

The seven suspects were the first to be indicted under Taiwan's Copyright Act since it was revised in March.

Taichung prosecutors said the seven suspects were part of a ring, led by a Taiwanese surnamed Ku (辜) who was conspiring with a member of China's video piracy syndicate to expand its illegal operations into Taiwan.

Investigators found that Ku had set up transmitters in Pingtung County, Taichung and New Taipei to provide TV content to customers by intercepting digital signals from legal broadcasting companies, the prosecutor's office said.

An increasing number of unscrupulous set-top box providers have been offering "unlimited" TV programs and movies that are mostly obtained or reproduced without the permission of the copyright holders, the office said.

Ku's ring had allegedly earned NT$10 million (US$316,000) over the past three years from such a service, according to prosecutors.

A set-top box is a device that enables a television set to become a user interface to the Internet and also enables a television set to receive and decode digital television broadcasts, allowing users to watch movies, drama series and other programs.

Under the revised Copyright Act, the maximum penalty for infringing on the economic rights of others by distributing audio-visual content via set-top boxes is two years in prison or a fine NT$500,000 (US$15,950).