Advertisers invest more and more on China’s prosperous Internet space but investment needs caution, The Wall Street Journal reported. From May 1 through July 31, advertisers spent 190 million US dollars on online ads in mainland China, nearly as much as on magazines, online-research company Nielsen/NetRatings reported. That still represents only about 3 percent of the total spending on advertising in China, while online-ad spending is about 6 percent of the total in the US. Advertisers are spending more online because already 123 million Chinese -- at last count -- are using the Internet and are increasingly turning to the Web to gather and share information, play games and explore hobbies in ways that haven't been seen in more developed markets. Only the U.S. has more Internet users. "In China, when the Internet works, it really works. The propensity among young people to respond to some online marketing mechanisms can be overwhelming," said Steven Chang, chief executive of Publicis Groupe SA media-buying agency Optimedia. For advertisers, the challenge now is figuring out how to spend their money well. "Everybody wants to put much more money in the Internet, but it is hard to hire enough people that understand it deeply." said Quinn Taw, the chief China strategy officer for GroupM, which manages WPP Group PLC's media agencies. Nielsen found that the biggest online-advertising spenders were in the automotive, computer, and electronics and consumer-goods industries. At the bottom of the list were banks and other financial-services companies, which dominate online spending in most other markets but account for 3 percent in China.