As companies move to restrict Web surfing at work, more of them are blocking access to MySpace than to Facebook, according to a survey released Wednesday by Web security company Barracuda Networks Inc.

While 44 percent of companies using Barracuda's Web filtering technology block access to MySpace, only 26 percent are doing the same to Facebook, according to an analysis of data contributed by several thousand customers, Barracuda said. While 19 percent of companies blocked both the sites, half said they block one or the other or both, the analysis showed.

Barracuda also conducted a separate survey of 228 IT security workers. It showed that 53 percent of businesses restrict Web surfing with automated Web filtering systems and almost two-thirds (65 percent) expect to enforce Web surfing restrictions in 2008. That would represent a 23 percent increase in the number of companies doing so. The top two reasons companies cited for enforcing Web surfing restrictions were virus or spyware protection (70 percent) and employee productivity drain (52 percent).

More than a third of the companies (36 percent) pointed to bandwidth concerns, while 28 percent cited liability issues as prompting them to restrict employee Internet access, the survey noted.

The analysis of the data from the Web filters shows that companies consistently block Web sites with content related to hacking, illegal drugs, intolerance and hate, phishing and fraud, offensive content, terrorism, violence, weapons and spam.

Companies had varying approaches to Web surfing, with 21percent actively monitoring employee Internet activity and 6% enforcing time restrictions on employee use of the Internet.

"Businesses are increasingly applying content-control mechanisms to protect their networks and maintain maximum organization productivity," Dean Drako, president and CEO of Barracuda Networks, said in a statement. "With the changing face of the Internet, companies need the flexibility to continuously monitor and customize Internet policy enforcement while providing their employees optimum use of the Web."