Top Chinese search engine Baidu Inc forecast strong sales that topped Wall Street estimates, after reporting robust quarterly earnings, shrugging off concerns that a weak economy could hit advertisers.

Baidu said spending by large customers was significantly better than it expected in the third quarter and its 80 percent rise in quarterly net profit was driven by spending by online retailers.

Shares of Baidu were up 7.2 percent at $148.50 in after-hours trade. Chinese Internet companies Sohu.com Inc and Sina Corp were up more than 4 percent.

China, with more than 485 million users, is the world's largest Internet market. Yet, with Internet penetration hovering around 36 percent and user sophistication outside the big cities still low, the potential for growth is huge.