Web portals Sina.com, Netease.com and Tencent Tuesday signed an agreement with the Internet arm of CCTV to get official rights to broadcast the Olympics, including the opening and closing ceremonies.

"With the extensive use of broadband and online streaming technology, online video has become one of the most popular Internet applications in China," Charles Chao, chief executive officer of Sina Corp, said.

The battle among Chinese portal sites began in 2005, when Sohu.com became the official sponsor of the Beijing Games, reportedly paying $30 million for rights to host the Olympics' official website and use its logo.

The company then claimed exclusive rights to host all sponsors' advertisements using the Olympic logo. In response, competitors, including Sina.com, Netease and Tencent, formed an alliance against Sohu.

The competition has intensified since China has overtook the United States as home to the world's largest national population of Internet users and with the Games fast approaching.

According to a JP Morgan report, the annual growth rate of China's online advertising market reached 50 percent last year, causing the sector to take over 6.7 percent of the country's 200 billion yuan ($29 billion) advertising market.

The Data Center of the China Internet said in a report Tuesday the Internet would become one of the top forms of media for broadcasting the Olympic Games.

It also estimated the number of Chinese who use the Internet at least once a week would reach 263 million in 2008.