Users of Baidu Tieba (百度贴吧) were found to be using the Chinese tech giant’s Reddit-like online platform to illegally sell laughing gas, according to several Chinese media reports over the weekend.

Baidu has since confirmed the reports to Caixin, as well as said that it has removed related illegal information and forwarded it to police. The company has also launched an inspection into key words such as “laughing gas,” “high balloons” and “nitrous oxide,” terms dealers use when selling the gas, an official statement on Monday said.

Consuming laughing gas, or nitrous oxide, for non-approved purposes is illegal in China. The gas slows users’ body responses when inhaled and causes giggling. It can be addictive and harmful to health.

Users in Baidu Tieba sub-forums dubbed “Balloons” and “Nitrous Oxide” reportedly posted information on how to purchase laughing gas and offered nationwide delivery.

The news has fueled concerns over Baidu’s ability to monitor content on its influential platforms. In 2016, a college student named Wei Zexi died after the company’s search engine led him to a costly and bogus experimental cancer treatment.