(Updates closing prices) SHANGHAI, July 30 (Reuters) - Shares in Hong Kong and China resumed their slump on Friday after rebounding in the previous session, with key indexes booking their worst monthly performance in years, as persistent concerns over regulatory crackdowns outweighed Beijing’s attempts to calm markets. China’s blue-chip CSI300 Index closed down 0.8% and posted its biggest monthly loss since October 2018, while the Shanghai Composite Index lost 0.42%, capping its worst month since May 2019. Hong Kong tech shares slumped again, pulling the benchmark Hang Seng index to its biggest monthly fall since October 2018. The Hang Seng closed down 1.4%, following Thursday’s 3.3% rally. Tech giants such as Meituan and Alibaba led Friday’s decline. Global investors have been dumping shares in Chinese companies after Beijing banned for-profit tutoring on core school subjects, following crackdowns earlier this year on the tech sector. The regulatory moves have revived worries about the risks of investing in China. The Hang Seng Tech Index plunged 2.56%, extending its weekly fall to 6.7%. A resurgence in COVID-19 cases in mainland China also dented investors’ risk appetite. An index tracking Chinese tourism stocks dropped 3.83%. Healthcare stocks on the mainland also fell sharply on worries the sector may be regulators’ next target. The markets had rebounded on Thursday after China stepped up attempts to calm frayed investor nerves by telling foreign brokerages not to “overinterpret” its latest regulatory actions. China Securities Regulatory Commission (CSRC) vice chairman Fang Xinghai held a meeting with global investment banks on Wednesday night in a bid to shore up confidence, while state media sang in chorus on Thursday in support of China’s capital markets. “We don’t think the signals from this recent news flow are enough for us to upgrade China to overweight,” Morgan Stanley said in a note, citing long-term concerns regarding the future of offshore China equities, and possible restrictions on foreign investment in Chinese companies. “Initial investor feedback indicates they remain concerned, and are looking for more formal guidance and actions to assuage these potential issues.” China’s official factory and service activity gauges for July will be released on Saturday. Growth in manufacturing is expected to slow slightly, according to a Reuters poll. (Reporting by Shanghai Newsroom; Editing by Kim Coghill) Our Standards: The Thomson Reuters Trust Principles.