Financial Secretary Paul Chan said on Sunday that Hong Kong must respect the mainland's socialist system and support the leadership of the Chinese Communist Party in line with the country's constitution.
Writing on his blog, he said he had learned more about how the One Country, Two Systems principle could be better implemented after attending a seminar on the Constitution Day on Saturday.
He said the Constitution has the highest legal status and legal effect, adding that the Constitution clearly states that the socialist system is the fundamental system of the People's Republic of China while leadership by the Communist Party of China is the defining feature of socialism with Chinese characteristics.
The finance chief added that the Constitution is also the basis for the introduction of the Basic Law and the establishment of the SAR.
"From the perspective of the Constitution, supporting the SAR's constitutional order means respecting China's socialist system and supporting the Chinese Communist Party's leadership, or else the SAR couldn't have existed," he wrote.
"Understanding the Constitution correctly helps us accurately and comprehensively understand Hong Kong's constitutional order and the One Country, Two Systems principle."
Chan noted that the introduction of the national security law and the overhaul of the electoral system here were also carried out based on the Constitution.
He said these changes had enabled Hong Kong's transition from chaos to order, and steered the city towards a new era of governance and prosperity.