The Conficker Working Group, an organisation set up to provide advice and help on the infamous worm, has launched a handy new checking tool to help users see if they are infected.

The Conficker Eye Chart features six images; the top row featuring anti-virus firms' logos and the bottom row operating systems other than Windows. The test is based on the fact that Conficker blocks access to over 100 anti-virus and security web sites, said the group.

"If you are blocked from loading the remote images in the first row of the top table above but not blocked from loading the remote images in the second row then your Windows PC may be infected by Conficker," say the explanatory notes on the site.

"If you can see all six images in both rows of the top table, you are either not infected by Conficker, or you may be using a proxy server, in which case you will not be able to use this test to make an accurate determination, since Conficker will be unable to block you from viewing the AV/security sites."

Despite unprecedented hype from various corners of the media prior to April 1 - the day when infected PCs were scheduled to connect to an update server - the predicted widespread disruption failed to materialise.

Experts have suggested that the criminals who own and operate the botnet would not want to risk losing the valuable network by triggering a major attack.

However, the virus still represents a risk to infected PCs and can be removed simply via a clean-up tool which many of the major AV vendors are now offering on their sites.