Antivirus specialist McAfee has announced it is to acquire web site content security firm SiteAdvisor (SA) for an undisclosed sum.

The year-old start-up specialises in software which checks if web sites’ content includes spyware, adware, spam, browser-based attacks or online scams, and then warns the user of potentially dangerous sites with red, yellow and green icons.

SiteAdvisor displays its safety ratings next to each search result when displayed by a search engine, or as a safety button on a browser toolbar as users surf the internet.

"We are very excited about the acquisition of SiteAdvisor. [It] has tested and rated a vast range of existing web sites, and their technology sets a new standard for safe searching, safe surfing, transaction security, anti-spam and anti-phishing," said McAfee's senior director of European marketing, Sarah Whipp. "Over 2006 we will be working on integration of the SA team into McAfee and defining our premium product offering feature."

As well as protecting consumers carrying out online transactions, SA's extensive records of dangerous web sites will boost the power and scope of McAfee's threat databases, according to the firm's chief scientist George Heron.

Andy Kellett of analyst firm Butler Group said the offering would add extra value to McAfee's anti-spyware systems in the business and consumer sectors.