A turf war between two rival software giants has sparked privacy fears among the mainland's 420 million internet users, with each side accusing the other of stealing information from computers. Users face being forced to choose between the mainland's most popular free instant-messaging service or its most popular anti-virus software. On one side of the fight is Shenzhen-based Tencent, which runs the Tencent QQ instant-messaging service, with 600 million accounts. On the other is Beijing-based Qihoo, which makes 360 Safeguard antivirus software, with 300 million users. 'It's an abduction of the social relationships of millions of users,' said Wang Fengchang , founder of website Laweach, which champions internet users' rights. He said the reputations of both companies had been damaged. Hong Kong QQ users have also expressed concern, with one local expert saying the row has exposed a lack of awareness of privacy and consumers' rights among mainland program developers. Qihoo initially accused QQ of scanning software and files unrelated to QQ, some of them private, without telling users. Tencent fired back, saying it was 360's new tool, Koukou Bodyguard, that put QQ users' account information at risk by scanning their accounts, passwords, friends and dialogue records when they logged onto QQ. The row heated up on Wednesday when Hong Kong-listed Tencent Holdings said it would shut down QQ on computers carrying Qihoo security software. It said it had been forced to 'make a difficult decision' and ask users to uninstall 360 software to protect their own security. On Friday it apologised for that decision and said that if users completely removed Koukou Bodyguard, released in October, it would allow QQ functions to resume. A Qihoo spokeswoman said yesterday that 360 Safeguard and QQ instant messaging remained compatible, but some people using Qihoo's internet browser could not open their QQ e-mail accounts or the QQ blog space. Xinhua quoted Qihoo executives as saying that central government ministries including the Ministry of Industry and Information Technology and the Ministry of Public Security had intervened, but a resolution has yet to be reached. Mainland media, including the China Youth Daily, reported over the weekend that it would take some time for the two companies to reconcile their differences. Qihoo vice-president Liu Jun said on Thursday: 'Qihoo doesn't want to involve millions of users in this turf war. We hope the internet will return to peace as soon as possible.' But after reports that the two companies had reached a temporary compromise, maintaining software compatibility for now, Tencent vice-president Liu Chang said on Friday that it was sticking to its guns. 'We will never compromise on this and will fight to the end,' she said. Liu Chang declined to say yesterday how many QQ users would be affected but Tencent president and chief executive Ma Huateng told the Yangcheng Evening News on Friday that about 100 million QQ users who used Qihoo products would be affected. Ma said QQ had started scanning for Trojans, programs that can enable a hacker to take control of a computer, since 2006, after the stealing of QQ accounts became widespread. 'Users complained that scanning before logging in was too slow, so we began doing it when users were online,' Ma said. Liu Chang said QQ's scanning module was reporting 15 million viruses and 1.7 million Trojans every day and the accusations against it were baseless. 'What we do is only to scan for Trojans, it's like going through a security gate before boarding a plane.' she said. Qihoo president Zhou Hongyi told the Yangcheng Evening News he was more worried about the security of computers after users uninstalled 360 Safeguard products than how many users had uninstalled it. 'Less than 20 per cent of users have uninstalled 360. As long as we have good products, users will come back.' Hostilities began on September 27, when Qihoo launched Privacy Protector, a tool it said should detect whether instant-messaging software was peeking at private computer files. The alerts it generated all pointed to QQ. And on October 29, it launched Koukou Bodyguard, which it said would protect QQ users' privacy, prevent Trojans and improve the speed of the instant-messaging service. Qihoo said more than 10 million users installed it within three days. Tencent denied breaching privacy and accused Qihoo of slander and foul play, suing for unfair competition and demanding 4 million yuan (HK$4.64 million) in compensation, the Legal Daily reported. Beijing's Chaoyang District People's Court accepted the case on Wednesday. By Friday, a group of mainland IT companies had formed an anti-Qihoo alliance. Search engine Baidu, anti-virus software producers Kingsoft and Keniu, and browser Maxthon sided with QQ, announcing their products would be made incompatible with Qihoo's new software, the China Youth Daily reported. About 85 per cent of more than 100,000 internet users surveyed by Mop, one of China's most influential online communities, said the two firms were only looking after their own interests and were ignoring users' rights. Nearly 75,000 internet users signed a Sina micro-blog campaign threatening to sue Tencent. One QQ user said he had long suspected QQ of scanning users' private data, but had not known that it had been doing so since 2006, in the name of safety. 'If it was truly as QQ said, only scanning for Trojans, why didn't it inform users and let them choose?' the user said. 'I suspect they had to do it either for commercial reasons or for passing the information on to the authorities. 'Although I'm worried about my privacy, I cannot give up QQ, which has become a social tool among friends, family members and business associates, and it's hard to find a replacement. But I think Tencent's kidnapping of users should be subject to legal penalties.' Isaac Mao, an internet researcher and director of the Social Brain Foundation, said both Tencent and Qihoo seemed to have breached users' privacy. 'QQ scans users' hard disks which are supposed to be beyond its function under the users' contracts,' he said. 'However, early versions of Qihoo 360 Safeguard did similar things before digging into people's software to locate and transfer people's private information, which is against the user agreement for anti-virus software. But this time, 360 focused on killing QQ.' By using internet users as leverage, Mao said, both internet giants had abused their monopoly position and were trying to disrupt users' normal use of software. Tencent's shutting down of QQ for users of Qihoo 360 software appeared to violate the agreement between the service provider and users, he said. Wang, of Laweach, said: 'Tencent is confident that users won't give it up. QQ users cannot afford to uninstall it right now, but that doesn't mean QQ is irreplaceable.' Turf war There are 300 million users of Qihoo's 360 Safeguard software Number of accounts using Tencent QQ instant-messaging service: 600m