Software manufacturers, and the US authorities, are taking action against scam artists who use scare tactics to make consumers buy worthless software.

Microsoft is among the companies who have filed lawsuits against these criminals.

The programmes listed in its complaints include Scan & Repair, Antivirus 2009, MalwareCore, WinDefender, XPDefender and WinSpywareProtect.

Most of the defendants are listed as "John Doe" because investigators do not yet know the identities of the people involved.

A case has also been launched by Washington State's Attorney General.

This lawsuit has been filed against a company based in Texas called Branch Software and Alpha Red and its owner James Reed McCreary IV.

It alleges that Mr McCreary's company "sent incessant pop-ups resembling system warnings to consumers' personal computers".


The complaint adds that these warnings "instructed users to visit a web site to download Registry Cleaner XP" at a cost of $39.95 (£21.70).

"We won't tolerate the use of alarmist warnings or deceptive 'free scans' to trick consumers into buying software to fix a problem that doesn't even exist", said Attorney General Rob McKenna.

It is hoped that lawsuits like this will crack down on this kind of scam, which Eric Sites, the chief technology officer with security firm Sunbelt Software, told the BBC is a growing problem.

"In the last six months we have seen an enormous uptick in the number of people getting infected by these scareware or spyware agents."

"They are becoming a lot more prevalent and the scare and scam is all about getting money out of the user", he told BBC News.