BEIJING - China's Ministry of Industry and Information Technology (MIIT) said Sunday it would investigate the dispute between Tencent and Qihoo 360 to determine whether actions by either company had broken the law.

The ministry also ordered the two Internet companies to end their brawl and publicly apologize before Nov 26 for their irresponsible behavior.

The announcement came after a business war between the two Chinese Internet giants had triggered a public outcry.

Tencent, China's largest Internet company, said on Nov 3 that it would shut down the QQ instant-messaging service on computers installed with security software made by Qihoo 360 following a dispute between the companies.

The unfair competition between the companies, especially the move to unilaterally shut the instant-messaging service, had affected users and caused "bad social consequences", the MIIT said in a statement.

The ministry announced it would take effective measures to ensure the fair, just and orderly competition within the Internet market to protect the interests of Internet users.

Tencent has 600 million registered QQ users, while Qihoo 360, China's largest free anti-virus software provider, has 300 million clients.

An on-line survey conducted by Sina.com showed about 80 percent of Internet users regarded the two giants' actions to be selfish and had harmed the interests of their clients.