Infections are continuing to spread at a steady rate and is taking over 30,000 systems per hour during peak times, experts have warned.

According to data collected by Network Associates' Hackerwatch.org, at least 1.2 million unique source IP addresses have been infected.

A detailed graph of the worm's progress can be found in http://www.hackerwatch.org/checkup/graph.asp.

Since the worm spreads quietly, and does not arrive as an email attachment, users may not immediately realise that they have been infected.

The first sympton users may spot is excessive use of home broadband connections.

Network Associates said in a statement: 'This worm has infected over one million users in a remarkably short period of time, and highlights the need for PC users to make sure they have comprehensive and constantly updated anti-virus and personal firewall solutions on their machines to prevent futureattacks from these types of internet threats.'