The "Life Stages" worm has yet to make a nuisance of itself in the UK though anti-virus companies are upgrading the virus to high risk and warning customers of the damage being done to U.S. email systems.

"We have upgraded the virus risk to category four, with five being the highest," said Katy Broomhead, spokeswoman for Symantec. The risk rating system is Symantec's own internal system, aimed at categorising the danger of different viruses. When the ILOVEYOU virus outbreak occurred in May, Symantec had the worm rated as a category five risk, the company's highest rating.

About a hundred Symantec customers have made submissions reporting the "Life Stages" virus in the U.S., but only five such submissions from multinational company customers have been made in Europe, Broomhead said.

"There have been no submissions from multinational companies in the U.K., though a handful of our consumer customers in the U.K. have reported the virus to us," Broomhead said, declining to name any of the companies that have been affected by the virus.