The number of Internet users in China, already the world's largest online market, hit 457 million in 2010 -- up 19.1 percent from the previous year, a government-linked industry body said Wednesday.

The figure marks an increase of 73.3 million users and means more than one-third of the country's 1.3 billion-strong population is now online.

The number of people surfing the web on mobile phones surged nearly 30 percent last year to 303 million, figures released by the state-backed China Internet Network Information Center.

China's spiralling online population has turned the Internet into a forum for citizens to express their opinions in a way rarely seen in a country where the traditional media is under strict government control.

The Internet has also become a lucrative marketplace. The value of online sales rose 22 percent in last year to 4.5 trillion yuan ($684 billion) as more price-sensitive consumers turned to the web for cheaper products amid rising inflation.

The sales data published by the China e-Business Research Center covers business-to-business, business-to-consumer and consumer-to-consumer transactions.

The growing strength and influence of the web population has prompted concern in Beijing about the Internet's potential as a tool for generating social unrest, and authorities have stepped up surveillance in recent years.

The government blocks web content that it deems politically sensitive in a vast system dubbed the "Great Firewall of China".