BEIJING -- The case between Chinese Internet giants Qihoo 360 and Tencent over monopolies and unfair practices opened at the Supreme People's Court (SPC) on Tuesday.

Antivirus software developer Qihoo 360 and China's largest Internet company Tencent have been engaged in a protracted legal war since 2010, attracting great public interest. The trial can be observed by the public through various media including newspapers, TV programs and the Internet.

Morning session proceedings included investigation, debate and mediation, with no ruling handed down.

Their feud began on Sept 27, 2010, when Qihoo 360 accused Tencent of invading the privacy of its users through QQ Doctor, a security program developed by Tencent for use with its popular QQ instant messaging service. Qihoo 360 claims that Tencent has used the software to scan and monitor users' personal information.

Following the complaint, Qihoo 360 released its own security software called "Koukou Guard" on Oct 29, 2010, claiming it would speed up QQ and offer better privacy. Tencent responded by warning its users that the "Koukou Guard" could cause QQ to malfunction.

In November, 2012, Qihoo 360 sued Tencent claiming it had abused its dominant position in the Internet marketplace.

In March, 2013, Guangdong Higher People's Court rejected Qihoo's suit against Tencent, and Qihoo has now appealed to the SPC.