Kaspersky has hit rival anti-virus vendor Rising Tech with a defamation lawsuit following Rising Tech’s recent controversial comments.

The dispute began back in May, when Kaspersky's antivirus software identified a Rising Tech update program as a virus. The fault only affected those users with both Kaspersky's and Rising's antivirus software installed, but it meant that the update element of Rising's antispyware software was deleted.

"We fixed the problem as soon as we could," said David Emm, senior technology consultant at Kaspersky.

However it seems that the Chinese vendor was not amused at all, and days later it alleged in a Chinese statement that Kaspersky's antivirus software had made 22 mistakes between November 2006 and May 2007.

"Rising were saying things about us which we weren't happy about," confirmed Emm. "In fact, what they were saying was so serious that our legal people felt we needed to take action."

The Chinese subsidiary of Kaspersky therefore filed a lawsuit against Rising late last month, accusing Rising of violating Chinese law by telling users that Kaspersky's software could damage their computers. In addition, it alleged that Rising defamed it by claiming the company engaged in anti-competitive practices and hired people to attack Rising in online forums and in the media.

The case is scheduled to be heard on 23 July in Tianjin No.1 Intermediate People's Court.

But this has not deterred the Chinese vendor, which responded to the Kaspersky lawsuit by escalating the situation, claiming that Kaspersky was the "king of false positives". Rising Tech then detailed another six instances in the past two weeks where Kaspersky's antivirus software allegedly misidentified system files from several programs as malware.