China has sent university students home and flooded streets with police in an attempt to disperse the most widespread anti-government protests in decades, as the country’s top security body called for a crackdown on “hostile forces”. In an apparent effort to tackle anger at the zero-Covid policies that originally sparked the protests, authorities also announced plans to step up vaccination of older people. Such a move is a vital precursor to loosening controls without mass deaths or overwhelming the health system in a country where there is almost no natural immunity to Covid, after nearly three years of trying to eliminate the virus. Following protests at the weekend, Beijing’s prestigious Tsinghua University, the alma mater of China’s leader, Xi Jinping, was among several universities to send students home and move classes and exams online, officially on the grounds that there had been a Covid outbreak. Police gathered in large numbers in squares and roads across China where protests had been held, and have put up barriers, including in Shanghai’s Urumqi Road, named for the capital of the Xinjiang region. The death of 10 people in a fire in Urumqi city was one of the triggers for the protests, amid claims they had been locked into their homes under Covid control rules. Originally centred on calls to end harsh controls, the protests morphed into broader demands including for democracy, and for Xi to step down. Before the crowds gathered, the demonstrations seemed unthinkable. Xi has ramped up surveillance, censorship and controls on civil society during his decade in power; just a month earlier, a banner hung by a solitary protester on a Beijing bridge made international headlines. In a sign of official concern, the Communist party’s central political and legal affairs commission, which oversees all domestic law enforcement in China, met on Tuesday. Its members blamed “infiltration and sabotage” by “hostile forces” and called for a crackdown, according to a readout of a meeting in the state news agency Xinhua. Chinese authorities often blame discontent on “foreign forces”, although the claim is likely to be shrugged off by many people in China frustrated by the fierce restrictions deployed to try to keep Covid out of the country. One weekend protest video showed a sarcastic crowd asking whether accusations about “foreign forces” referred to Marx and Engels, the fathers of communism, whose works still feature on the Chinese syllabus. The protests appear to have blindsided authorities. The foreign ministry spokesperson, Zhao Lijian, a champion of hyper-aggressive “wolf-warrior” diplomacy, was rendered briefly speechless on Tuesday by a question about whether the government would consider changing course on Covid after the demonstrations. He silently shuffled papers for almost half a minute, before asking for the question to be repeated and then responding that it “didn’t reflect what happened”. However, Chinese authorities have detailed plans to deal with any form of unrest, and security forces are already trying to identify and round up some who took part. Two protesters told Reuters that callers identifying themselves as Beijing police officers asked them to report to a police station on Tuesday with written accounts of their activities on Sunday night. A student also said they were asked by their college if they had been in an area where a protest happened and to provide a written account. “We are all desperately deleting our chat history,” said another person who witnessed the Beijing protest and declined to be identified. Eyewitnesses reported police asking people for their phones to check if they had virtual private networks (VPNs) that can be used to access sites blocked in China including the Telegram app, a key communications channel for weekend protesters. People were also sharing instructions on Telegram about how to keep phone data safe from random police checks, including apps or settings to quickly clear data. “What to do if your phone is stolen or taken by the police – this little guide may prevent unpleasant situations down the road,” one message read. Xi has put “zero Covid” at the heart of his government agenda this year, as the rest of the world moved away from strict pandemic controls, even though it has crippled the economy, isolated China and caused deaths and great personal misery across the country. The low vaccination rate among older people is one of the major hurdles to easing the zero-Covid policy. They have been far more averse to vaccination than younger generations. Under a new plan for “strengthening coronavirus vaccination of the elderly”, the national health commission said it would target more vaccinations at people older than 80 and reduce to three months the gap between basic vaccination and booster shots for elderly people. Some individuals who have refused vaccination would start having to explain why, officials said. China has not yet approved mRNA vaccines, proven to be more effective, for public use. China logged 38,421 domestic infections on Tuesday, slightly down from record highs seen over the weekend and low when compared with caseloads seen in western countries during the height of the pandemic. One official acknowledged “the problems reported by the people recently”, which he blamed on the implementation of government policies at the local level rather than the policies themselves.