, the leading search engine in China, can probably count its MP3 search tool as the primary boosting factor for its high growth. But the music search service which tracks and links to (mostly illegally posted) songs has brought its share of trouble too, with a Chinese music industry group now suing the site over alleged copyright violation.

The lawsuit, filed by the Music Copyright Society of China, accuses Baidu of profiting by providing users online music “without approval, and through unfettered piracy,” and asks for proper compensation. The move reflects the fact that the local music companies and the domestic artists in China are increasingly growing wary of the Baidu’s free music search feature. It also follows a similar lawsuit by Universal Music, Sony BMG and Warner Music.

This comes at a time when Google, which is hoping to catch up to Baidu in the Chinese market, has announced it will work with Top100 to offer licensed music for users to download at no cost.