BEIJING - China had $131 billion worth of private start-ups by the end of 2016, nearly doubling the figure of the year before, said an official with Ministry of Science and Technology.

Zhang Zhihong, director of the ministry's Torch High Technology Industry Development Center, made the remarks while opening an institute for small and medium enterprise research in Tianjin over the weekend.

He used the term "unicorn," rarely used by Chinese officials, which refers young, unlisted companies with a market value of over $1 billion, based on private funding sources.

China's unicorns are spread over 16 cities, but mostly in Beijing, Shanghai, Shenzhen, and Hangzhou. The majority are innovation-driven tech businesses, Zhang said.

A report published by the torch center earlier this year said half of China's unicorns are in Beijing's Zhongguancun, home to China's three super-unicorns worth over $10 billion: Xiaomi, Didi Chuxing, and Meituan.

One third of Zhongguancun's unicorns were born after 2014. They focus on four domains -- e-commerce, culture and entertainment, internet finance, and transportation, according to the report "Development of China's Unicorn Enterprises in 2016".

In fact, Zhongguancun is second only to Silicon Valley as the most concentrated area for tech unicorns in the world, the report says.

Zhang said a pro-innovation business environment, conductive policies, and good services are key to the growth of unicorns.

"Unicorns have become important engine to maintaining medium-high growth and to transforming industry," Zhang said. "Their emergence is key to development of the sharing, smart, and platform economies."