China’s biggest tech stocks dropped after the country approved a strict data privacy law, prompting renewed concerns among investors over the intensity of Beijing’s regulatory crackdown.

In Hong Kong on Friday, the Hang Seng Tech index of China’s largest internet and ecommerce stocks including Tencent and Alibaba dropped 2.5 per cent after state news agency Xinhua announced the law had been passed and would take effect on November 1.

The report gave little detail on the contents of the law but said it would clarify how sensitive personal data could be processed, require internet platforms to establish “robust personal information protection compliance systems” and stressed that companies “must not excessively collect personal information”. An earlier draft of the law substantially curtailed Chinese companies’ ability to harvest data without users’ consent and imposed fees of up to Rmb50m ($7.7m) or 5 per cent of annual revenue for serious violations.