Hong Kong effectively connects the world's two largest economies of the United States and China, Hong Kong Chief Executive Leung Chun-Ying said here Tuesday.

At the "Think Asia, Think Hong Kong" symposium, which attracts more than 200 Hong Kong and Chinese mainland officials and business leaders, Leung said Hong Kong provides the most efficient way for US companies to reach the Chinese mainland and Asian markets.

He said as a city of 7 million people, Hong Kong is the 10th largest market for US exports and bilateral trade volume has tripled in the past decade.

"There are currently 1,300 US companies operating in Hong Kong and half of them set up regional headquarters here. They know if their products and services sell well in Hong Kong, they will sell well throughout the country, a market with a potential of 1.3 billion customers," the chief executive said.

Leung said the Chinese mainland and Hong Kong Closer Economic Partnership Arrangement (CEPA) eliminates import tariffs and provides preferential market access in 48 sectors, and US companies operating in Hong Kong can also enjoy full benefits of the CEPA.

Francisco Sanchez, US under commerce secretary for international trade, also highlighted Hong Kong's unique position as it links the west to the east.

"When we think about doing business in Asia, we have to think about Hong Kong, because Hong Kong is in many ways our gateway to the continent," Sanchez said, adding that this program provides necessary information and expertise to any business that hopes to expand exports and investment in Asia.

The event, held by the Hong Kong Trade Development Council, is the largest promotion that Hong Kong has ever organized in the United States.

It is also Leung's first overseas trip since he became chief executive of the Hong Kong Special Administrative Region of China in 2012.