The Cyberspace Administration of China, the country's top internet watchdog, announced on Monday that it has launched a cybersecurity probe into Boss Zhipin, a mobile recruitment app, and truck-hailing apps Yunmanman and Huochebang in accordance with laws and regulations to prevent data security risks, safeguard State security and protect public interests.

Boss Zhipin, which is operated by Chinese tech company Kanzhun, said it will actively cooperate with government agencies in the security investigation, with comprehensive screening of security risks.

"We'll continuously enhance our cybersecurity awareness and effectively implement our enterprise's responsibilities and obligations," the company said.

Full Truck Alliance Co, which runs Yunmanman and Huochebang, gave a similar response to the probe on Monday, saying it will conduct a thorough security review and further improve its cybersecurity system and technical capabilities during the investigation period to protect national security and public interests.

During the investigation, the three apps must halt the registration of new users to prevent expansion of security risks, the administration said.

On Friday, the authority launched a cybersecurity investigation into Didi Chuxing, a popular ride-hailing app, saying that new users cannot register with the app while the investigation is underway.

Later on Friday, Didi pledged to actively cooperate with the security probe and fully address network security risks.

On Sunday, the administration ordered app stores to remove Didi Chuxing for its illegal collection and use of users' personal information, requiring the app to rectify its problems according to laws and national standards to protect the safety of users' information.

Didi Chuxing said via micro blog that it has halted the registration of new users since Saturday, adding that it will remove the app from stores and correct problems in line with the authority's requirements.

The company said those who have already downloaded Didi Chuxing could continue using the app.

Zuo Xiaodong, vice-president of the China Information Security Research Institute, said the security investigations of these enterprises reflect the country's measures to strengthen the prevention of cybersecurity and data security risks.

"The moves showed China has attached great importance to security issues. When finding security risks or potential problems, it will take action as quickly as it can, because cybersecurity means national security," he said.

Zhao Zhanling, a lawyer from Beijing Yunjia Law Firm, said the probes are an implementation of the Cybersecurity Law and the National Security Law as well as a regulation on cybersecurity investigation.

After the Data Security Law, which was passed last month, takes effect in September, "such probes may be conducted in a regular manner with the country's increasingly high attention to cybersecurity," Zhao added.