Pro-democracy protesters retreated from Hong Kong's airport on Wednesday following two days of hugely disruptive rallies that turned violent and plunged the global financial hub further into turmoil. The protests ended early Wednesday morning following a series of clashes in which a policeman drew his gun after being beaten by demonstrators and other officers fired pepper spray. The rallies paralysed one of the world's busiest travel hubs, deepening a 10-week crisis that is the biggest challenge to Chinese rule of Hong Kong since its 1997 British handover. US President Donald Trump, who has come under fire over his stance towards the protests, deepened fears Beijing may be prepared to stage a military intervention to end the unrest, saying on Tuesday his intelligence had confirmed Chinese troop movements toward the Hong Kong border. China's Hong Kong affairs office condemned what it called "near-terrorist acts" at Hong Kong's airport and reiterated support for local authorities to severely punish those responsible. The Hong Kong and Macao Affairs Office, in a statement issued on Wednesday, also strongly condemned attacks against a reporter from China's Global Times newspaper and a traveller at the airport by what it said were violent protesters. The unrest, which has seen millions of people take to Hong Kong's streets, was sparked by opposition to a planned law that would have allowed extraditions to mainland China. But it quickly evolved into a much broader campaign for democratic freedoms. On Monday and Tuesday, thousands of protesters wearing their signature black T-shirts gathered at Hong Kong's airport, forcing hundreds of flights to be cancelled. Late on Tuesday night, the protests descended into a series of violent confrontations with police. Demonstrators turned on two men, fuelled by suspicions within their ranks about undercover police or spies. The first man was held for about two hours before eventually being led away in an ambulance.  Another man, wearing a yellow journalist vest, was surrounded, zip-tied and then beaten by a small group who accused him of being a spy. In a tweet, Hu Xijun, the editor of China's state-controlled Global Times tabloid - which has vociferously condemned the protests - said the man was a journalist working for the paper. A front-page commentary on the overseas edition of the Communist Party's official People's Daily newspaper said on Wednesday Hong Kong had reached a critical juncture. "Using the sword of the law to stop violence and restore order is overwhelmingly the most important and urgent task for Hong Kong!" it said. Hong Kong protests | Read more Another commentary by a Shenzhen University researcher, published by the China Daily, said the central government should deal with Hong Kong issues more decisively. However, Chinese state media has stopped short of calling for military action to deal with the protests. Five people were detained in the latest disturbances, police said, bringing the number of those arrested since the protests began in June to more than 600. By early Wednesday, most protesters had left and many flights were operating as scheduled in the morning. However, it was unclear if the protesters, who have no public leaders and organise via social media, would return to the airport. The Airport Authority has obtained an injunction to remove demonstrators but enforcing it may prove difficult, as the hub is designed to make entry as fast and efficient as possible. The Chinese government has repeatedly signalled the protesters are reaching the limits of the "one country, two systems" legal framework that gives Hong Kong its autonomy. Authorities in Beijing on Monday described some of the violence as "terrorism", and state-run media this week began promoting videos showing security forces gathering in Shenzhen just across the border from Hong Kong. Mr Trump on Tuesday said his intelligence had confirmed Chinese troops were gathering across the border. "I hope it works out for everybody including China. I hope it works out peacefully, nobody gets hurt, nobody gets killed," he said.