The director of the Hong Kong and Macau Affairs Office, Xia Baolong, on Monday hailed the SAR government for completing a "historic mission" last month when it passed the territory’s homegrown national security law, adding the city had a bright future ahead of it.

Beijing's top man overseeing SAR affairs also said the country's support for the Hong Kong would not waver.

He told the opening ceremony of the National Security Education Day via video link that the legislation, which he likened to a "sophisticated security system", provided the best possible opportunity for Hong Kong to focus on its economy.

Xia noted many mega events had been held since Basic Law Article 23 national security legislation was passed and global business leaders have cast their vote of confidence "with sincerity and real money”.

"Hong Kong still has the best business environment in the world, and is the best place to start a business, make money and realise one's dreams. It is like the sun in the universe. Its shine can never be covered by dark clouds," he said.

"Hong Kong's prosperity will not be harmed just by a few articles and some clamour... Let those who can't see the good things of Hong Kong lament. Hong Kong's tomorrow is destined to be bright."

The Beijing official said the governing principle of "One Country, Two Systems" would not change and does not need to change, adding that Hong Kong continues to have the nation's backing.

“Because of 'One Country, Two Systems', Hong Kong's needs will be met by the motherland. No matter what difficulties and challenges Hong Kong faces, the support from the motherland will only strengthen, not weaken," Xia said.

"There will be more policies supporting and favouring Hong Kong to come."

He also urged the city to consolidate and enhance its unique status and advantages, while seeking and embracing changes.

"We cannot use the old perspective from yesterday to look at today's new situation. We cannot use the old mindset from yesterday to solve today's new problems," he said.

"We need to unite and look ahead, use new mindsets, new solutions and new paths to tackle problems. We must dare to say words that have not been said by our predecessors, and do things that have not been done by our predecessors."

Xia added the city should focus on attracting overseas talent and develop areas such as fintech, green finance and the digital economy.