More than half of Chinese netizens are willing to turn their backs on China's dominant instant messenger, QQ, after its owner Tencent Holdings Ltd pushed people to choose either QQ or a popular anti-virus program by Qihoo 360.

When asked "which program will you desert between QQ and 360 if you have to", more than 57 percent of 1.5 million participants voted to get rid of QQ, while 23 percent chose to sweep out 360, according to a poll on sina.com by 8:30 pm on Thursday. Another 19 percent were undecided.

Two pop-ups by Tencent on a netizen's computer in Fuzhou, Fujian province on Thursday say instant messaging software QQ is not compatible with the security software by Qihoo 360.

Tencent said QQ has more than 600 million active accounts, while 360 said the number of its users has surpassed 300 million.

"We have just made a very difficult decision ... we have decided to stop running QQ on computers installed with 360's software," Tencent said in an open letter on Wednesday night.

Tencent said it felt sorry for the inconvenience to QQ users, but it would not change the decision unless 360 stops its "malicious slander".

"A new tag-on service run by 360 has affected functions of QQ. With 360 installed, we cannot guarantee the safety of our service," Tencent said in a pop-up on the screens of millions of QQ and 360 users on Wednesday night.

Qi Xiangdong, president of Qihoo 360, said Tencent's move was disastrous for China's Internet users, as it might lead to a large outbreak of viruses.

"Our 360 software is eliminating about 60 million Trojan horses daily for Chinese Internet users. If they uninstall it, the scale of virus attacks will be beyond imagination," Qi said.

On Wednesday night, 360 also released an open letter, calling on netizens to boycott QQ for three days to protest Tencent's attempt to "kidnap" users' interests.

The war between Tencent and 360 started in late September when Tencent upgraded its security related software, threatening 360's market share. After that, 360 alleged QQ was secretively scanning users' computers and leaking their private information. Then 360 offered a new service to prevent privacy leaks, and Tencent has since accused 360 of slander and foul play.

Regardless of who should be blamed for turning users' computers into a battlefield, users were more worried about saying goodbye to one of their programs.

"My brothers and sisters use QQ, my colleagues and classmates use QQ, even my clients do business with us through QQ. I don't like QQ's threat but I just can't stop using it," said 32-year-old Fan Qicheng, salesman at a State-owned company that has installed 360's free anti-virus software.

But Huang Min, a white-collar worker in Nanjing, said she will choose 360 and turn to MSN, a similar instant messaging software, if necessary.

"Many of my QQ friends are also on my MSN. It won't be much trouble," she said. "But 360 is important to my computer safety."

Chen Jinqiao, deputy chief engineer of the China Academy of Telecommunication Research under the Ministry of Industry and Information Technology, told China Daily on Thursday that the ministry has stepped in to mediate.

Many netizens also reported on Thursday that the two programs can still run at the same time on their computers, though others complained they conflict with each other.