An online malware measuring tool has unexpectedly rated UK PCs as having the lowest level of infection in Europe.

The Nanoscan tool, which can be downloaded as a plug-in from the site of owner Panda Software, put the UK in bottom spot last week, with only 8.1 percent of those scanned showing active malware. By a separate measure, that of ‘latent’ or inactive malware, however, the UK fared less well, reaching 20.7 percent.

Top of the infection list for active malware was France (28.2 percent), Mexico (23.1 percent), Brazil (18 percent), the US (17.8 percent), and Argentina (17.4 percent).

The figures appear to show very high levels of infection, but the results only rate those who visited the site and asked to be scanned. These individuals would be expected to show a bias towards having infected PCs. The company has created its own global malware map from the data, which is collected from thousands of mostly consumer PCs every 15 minutes.

Interestingly, almost 8 percent of those scanned and who showed active threats also had anti-virus software installed, which appears to support the company’s controversial view that conventional signature-based malware detection is no longer enough to protect PCs.

“These figures prove that it must be complemented with online tools such as Nanoscan and Totalscan, which are capable of detecting more malicious codes than the solutions installed on users’ computers” said Luis Corrons of Panda Software.

Nobody knows for sure how many PCs are infected with malware at any one time, though last year Microsoft came up with the more optimistic figure of one in 300 Windows PCs in its own research.

Critics might point out that, flawed though anti-virus systems might be, they are no worse than online scanning tools, which are often promoted as marketing tools for paid-for products. This is the case with Nanoscan. Anyone passing the malware test with Nanoscan is invited to try the more advanced but paid-for Totalscan software.