China's Internet giant Sohu's search engine arm Sogou on Wednesday filed a lawsuit against Qihoo 360, a New York-listed Internet security company, for unfair competition.

Qihoo 360 is accused of using its free Internet safety products to "induce and cheat users, prevent them from using the Sogou browser through destructive technical means, and damage Sogou's service integrity to Internet users," according to Xi'an City Intermediate People's Court in northwest China's Shaanxi Province.

Sogou is demanding an open apology from Qihoo 360, and compensation of 45.5 million yuan (7.4 million US dollars).

The court accepted the case, but did not disclose when the trial would open.

Also on Wednesday, Qihoo 360 announced it would sue Sogou and its CEO Wang Xiaochuan for unfair competition and damaging its reputation at two separate courts in Beijing, requesting total compensation of 51 million yuan. The courts have not confirmed the lawsuits.

Established in 2005, Qihoo 360 was listed in New York in 2011, and has a current market value of over 10 billion US dollars.

The company lost a lawsuit in April, when it was accused of malicious competition and fined 5 million yuan as compensation to China's Internet giant Tencent, the highest that has ever been ordered in an Internet competition lawsuit in China.