HONG KONG — A company listed in Hong Kong that is caught up in a corruption investigation focused on China’s biggest state-owned oil conglomerate said on Thursday that Chinese investigators had questioned it about projects, seized documents and frozen some bank accounts.

The company, Wison Engineering Services, disclosed the details in an announcement to the Hong Kong Stock Exchange. They are the latest public signs of a spreading corruption inquiry that has brought down one senior Chinese Communist Party official, Jiang Jiemin, and encroached on Zhou Yongkang, the retired head of China’s powerful domestic security administration.

“As part of their investigations, the regulatory authorities made enquiries about certain projects” of Wison and its subsidiaries, and have “taken books and records and frozen certain bank accounts,” the company said.

Hua Bangsong, the billionaire chairman and founder of Wison, has been helping authorities in China with the investigation, the company said this month. In its latest announcement, Wison said it had been unable to contact Mr. Hua, and that Zhao Hongbin, a financial manager of a Wison subsidiary, was also “assisting in the investigation.”