BEIJING, July 30 (Reuters) - China"s Ministry of Industry and Information Technology (MIIT) said on Friday that big tech companies should step up the management of exporting "critical data" as well as their risk assessment of data security. The Internet Society of China, a non-governmental organisation, has met representatives from Alibaba (9988.HK) and its fintech affiliate Ant Group, Tencent (0700.HK), ByteDance, Meituan (3690.HK), Baidu (9888.HK) and others to address the implementation of China"s Data Security Law, under the authorisation of MIIT, the ministry said in a statement. China has been revamping its policy towards data security and user privacy. In September it will implement its Data Security Law, which requires companies that process "critical data" to conduct risk assessments and submit reports to authorities. It also calls on organizations that process data affecting China"s national security to submit to annual reviews. MIIT specifically called for tech companies to understand the "importance of safeguarding national security" as well as "earnestly fulfill their data protection obligations." The Cyberspace Administration of Cyberspace (CAC) this month launched a cybersecurity review into ride-hailing giant Didi Global, calling for it to stop adding new users and for app stores to remove it. read more Tencent"s ubiquitous messaging app WeChat has temporarily suspended registration of new users in mainland China as part of a technical upgrade "to align with relevant laws and regulations." Tencent said the registration services will be restored once the upgrade is complete, in early August. read more Reporting by Yingzhi Yang and Brenda Goh; Editing by Jason Neely and Mike Harrison Our Standards: The Thomson Reuters Trust Principles.