China’s top security agency has called for a crackdown on nationwide protests that have spread to 15 cities and Hong Kong. Reports say the police presence has increased in Beijing and Shanghai, and some protesters have been tracked down and interrogated. Online censorship has also tightened on sites, including Twitter. Demonstrations started last week after a deadly apartment fire fuelled public anger over strict COVID restrictions and now pose an unprecedented challenge to the leadership of President Xi Jinping and the Chinese Communist Party. Some protesters are calling for free speech and democracy in numbers not seen since the 1989 Tiananmen Square protests. Many have been holding up blank sheets of paper or displaying other creative symbols of defiance, including mathematical equations to evade government censors. While relaxing some restrictions on Monday in response to the protests, the Chinese Government said it is standing by its ‘COVID-zero’ policy.