The war between Baidu Inc, owner of China's most popular Internet search engine, and Qihoo 360 Technology Co Ltd, a newcomer in the field, is heating up.

The share price of Baidu stumbled on Wednesday after Qihoo announced it was using a self-developed search engine.

Qihoo's announcement came after earlier reports speculated that the company, famous for its anti-virus software products, was grabbing results from other Web search engines to create its own.

"The company holds the patent of 360 Search, a self-developed engine that took us seven years to develop," the company said, adding that Qihoo is equipped with "Web search engines".

Many analysts believe Qihoo is not yet ready to challenge Baidu, which became the nation's top search giant after Google Inc left the Chinese mainland in 2010, investors have expressed their concerns.

Baidu's share price declined more than 6 percent on the Nasdaq on Wednesday to close at $113.10. The company's stock has dropped nearly 8 percent since Aug 23, according to US financial website CNNMoney.

Qihoo edged up 2.04 percent on the New York Stock Exchange on the same day.

Baidu, which generates nearly 80 percent of online advertising revenues in the nation's Web searching sector, on Tuesday afternoon started to redirect search traffic coming from Qihoo to its own home page.