The Secretary for Innovation, Technology and Industry on Sunday said government backing and an efficient market are both necessary, if plans to expand a Shenzhen-Hong Kong tech zone were to succeed.

Sun Dong's comments came days after officials unveiled the development outline for the SAR section of the Hetao Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone.

The first phase of the development now covers twice the gross floor area compared to the original scheme.

Speaking on a radio programme, Sun said he explained to his friends in Shanghai what Hetao is really about.

"I told them today's Northern Metropolis is like Shanghai's Pudong district in the old days, and that Hetao is equivalent to Pudong's Oriental Pearl," he recalled.

"They immediately understood that this is extremely important for Hong Kong's future development."

The minister added mainland officials faced similar challenges when they developed Pudong in the 1990s. But they made it happen, even with a limited budget, he said.

Asked about US president-elect Donald Trump's tech restrictions on China and how it might affect Hong Kong, Sun said the city should work more closely with the mainland and strengthen its own technology infrastructure to cope with the complex global environment.

The innovation chief also called on local tech companies to procure supplies and equipment from different sources, instead of relying too much on a single market.