The high-profile visit by Xi, also the General Secretary of the ruling Communist Party of China, is his first to the gleaming city since becoming the top leader in 2013. It also comes three years after mass pro-democracy rallies crippled parts of the Asian financial hub for months.
Xi's warning came at a gathering to mark two decades of years of Chinese rule in Hong Kong and swearing-in of pro- Beijing new Chief Executive Carry Lam and her Cabinet.
"Any attempt to endanger national sovereignty and security, challenge the power of the central government and the authority of the Basic Law of the HKSAR (Hong Kong Special Administration Region) or use Hong Kong to carry out infiltration and sabotage activities against the mainland is an act that crosses the red line, and is absolutely impermissible," Xi, also General Secretary of the ruling Communist Party of China, said.
Also Read
Hong Kong has been simmering for the past few years with massive demonstrations, including prolonged "occupy protests" against China screening candidates to contest elections.
Sounding exasperated over the recurring protests, Xi said people in Hong Kong was freer than ever.
"The people of Hong Kong, now masters of their own house, run their local affairs within the purview of autonomy of the Hong Kong Special Administrative Region (HKSAR)," he said in a nationalistic speech which emphasised Beijing's control over the city, now a special administrative region of China.
Xi stressed the importance of having a correct understanding of the relationship between "one country" and "two systems", saying that the system was advanced to realise and uphold national unity.
"We must both adhere to the 'one country' principle and respect the differences of the 'two systems,'" he said.
Beijing will unswervingly implement the policy of "one country, two systems" and make sure that it is fully applied in Hong Kong without being bent or distorted, he said.
Hong Kong cannot afford to be torn apart by reckless moves or internal rift amid the intense global competition, Xi cautioned.
However, "making everything political or deliberately creating differences and provoking confrontation will not resolve the problems," Xi said. "On the contrary, it can only severely hinder Hong Kong's economic and social development."
"Hong Kong is an affluent society, but it also faces enormous challenges posed by profound changes in the global economic environment and the increasingly intense international competition," he said.
The concept of "one country, two systems" gives expression to the vision of peace and harmony in the Chinese culture, and it embodies a very important tenet, namely, seeking broad common ground while setting aside major differences, Xi said.
Xi said Hong Kong should always focus on development as the top priority.
"I am convinced that the practice of 'one country, two systems' in Hong Kong will write a new chapter," he said.
As Xi spoke, thousands of pro-democracy protesters set off from Victoria Park. The key themes of the protests were reclaim Hong Kong and release of Liu Xiaobo, the jailed Chinese dissident and Nobel Peace prize winner who was recently diagnosed with cancer.
Another protester said more and more people were getting frustrated by the increasing influence of Beijing on the city, which is supposed to enjoy a high degree of autonomy.
He said that growing concerns over Liu and Beijing's recent claim that the Sino-British Joint Declaration "no longer has any realistic meaning" could spark more people to take to the streets.
Disclaimer: No Business Standard Journalist was involved in creation of this content