In April, Leung and other senior Hong Kong government officials paid a three-day visit to construction sites in the Greater Bay Area.

Hong Kong will give full play to its competitive advantages while tapping into the complementary strengths of its partner cities, said Leung, who on July 1 will step down to make way for incoming chief executive Carrie Lam.

With the completion of several giant infrastructure projects, including bridges, highways and bullet trains connecting the city with neighboring regions on the mainland and Macao, he said Hong Kong will see a blueprint to play a crucial role as the "super coordinator" between the mainland and the world.

"Our advantages are obvious and unique under the principle of one country, two systems. Our services, including legal services, enjoy preferential access to the mainland market under the Closer Economic Partnership Arrangement," he said.

Leung said Hong Kong also is a highly international society, and the international community is familiar with its legal system and the common law.

"In short, our trilingual ability and international network make us an ideal partner in legal services for both the mainland and international companies," he said. "We can help foreign enterprises grow into the mainland market, and partner with mainland firms in expanding into foreign markets, including those along the Belt and Road."

Last year, the SAR's government set up a Belt and Road office to map out strategies and policies, helping local companies and professionals in reaching out. The Hong Kong Monetary Authority's Infrastructure Financing Facilitation Office, also set up last year, has helped companies invest in infrastructure projects.