US-listed Sina Corp, China's biggest web portal company, reported a jump in first quarter net income of 22.9 percent from the same period last year, boosted by strong advertising sales growth.

Related readings:  Nasdaq hunting for business in China Sina.com to provide copyrighted music on line  Sina posts 15% drop in Q4 profit Sina.com signs deal with TV channel

Net income rose to US$8.6 million, or 15 US cents per share, by US accounting standards, from US$7 million, or 12 US cents, in the first quarter of last year, the company said in a statement on its Web site on Tuesday.

Sales climbed ten percent to US$51.3 million, beating the company's earlier estimate of 48 to US$50 million, according to the statement.

However, the sales represented a nine percent drop from the US$56.4 million in the fourth quarter of last year, it said.

Advertising revenue soared 43 percent to US$31.8 million from the first quarter last year, but it dropped 11 percent from the fourth quarter of last year.

The firm said the advertising revenue declined from the fourth quarter because the first quarter usually saw the weakest growth in advertising business.

The company, which listed on the Nasdaq exchange in 2001, said mobile value-added services declined 20 percent to US$18.2 million from a year earlier.

It forecast sales would reach 58 million to US$60 million in the second quarter with advertising revenue rising to 40 million to US$41 million.

China's rising number of net users has been fuelling the growth in Internet-related businesses.

The country had 137 million net users by the end of last year, an increase of 26 million from the end of 2005, according to the China Internet Network Information Center.

(For more biz stories, please visit Industry Updates)