BEIJING, Aug. 4 (Xinhua) -- China's State Post Bureau has launched an investigation into STO Express Co., Ltd. regarding workplace safety issues, the bureau said on Tuesday.

Since the beginning of this year, multiple workplace safety accidents have taken place at enterprises operating express delivery services under STO Express trademarks, trade names and waybills, according to the bureau.

Safety hazards have also been repeatedly found at their business sites during inspections.

The bureau said STO Express had failed to properly manage workplace safety at related enterprises and had not implemented unified safety management as required. It has filed a case for investigation into the company in accordance with the law.

STO Express is one of China's major courier service providers.