Chinese internet search engine Baidu has come under attack from the country’s technology regulator after a flood of complaints over false advertisements, pornography and leaks of personal information.

Nasdaq-listed Baidu has enjoyed a rapid rise, helped by Google shutting down its China site over censorship concerns in 2010, and along with Alibaba and Tencent is one of China’s internet trinity. However, disappointing half-year earnings in July suggest its star may be waning.

The latest scandal shows it is not too big to fend off criticism of unethical behaviour — or to evade the attentions of the regulator. The State Internet Information Office said it had grilled Baidu executives on Friday and that the company would face unspecified punishment.