When it comes to protecting the privacy of their children, US parents give social networks a failing grade.

Three out of four parents polled by Zogby International believe social networks are not doing a good job of protecting kids' online privacy.

The survey was conducted for Common Sense Media, a nonprofit organization dedicated to helping families navigate the world of media and technology.

Ninety-two percent of parents said they are concerned that children share too much information online, and 85 percent said they are more concerned about online privacy than they were five years ago.

The poll found a great deal of concern about geo-location services which pinpoint someone's whereabouts.

Ninety-one percent of parents said search engines and social networking sites should not be able to share the physical location of children with other companies until parents give authorization.

"The poll results present a clear divide between the industry's view of privacy and the opinion of parents and kids," Common Sense Media chief executive and founder James Steyer said.

"American families are deeply worried about how their personal information is being used by technology and online companies, yet the companies appear to be keeping their heads deep in the sand," Steyer said.

Technology companies need to step up but parents, children, schools and government also need to do more, he said.

"Parents and kids have to educate themselves about how to protect their information," he said. "Schools should teach all students and their parents about privacy protection.

"And finally, policymakers have to update privacy policies for the 21st century," he said.

According to the Zogby poll, more than 60 percent of parents want the US Congress to update online privacy laws for children and teenagers.

"Parents want far more education and leadership about online privacy, and they clearly want the industry and the federal government to update privacy policies," Steyer said.

"There are some common sense solutions to these problems, such as 'opt-in' policies that require companies to let parents know how information will be used before it's collected and requiring companies to use short and simple privacy policies instead of confusing and dense policies," he said.

Steyer, Deputy Education Secretary Anthony Miller, Federal Trade Commission chairman Jon Leibowitz and Federal Communications Commission chairman Julius Genachowski launched a "Protect Our Privacy - Protect Our Kids" campaign aimed at protecting the personal information and reputations of children online.

The campaign includes consumer tips, information, and videos and a privacy curriculum for teachers and schools around the United States.

Zogby polled 2,100 adults in August. The poll has a margin of error of plus or minus 2.2 percentage points.

In other findings, Zogby found that 68 percent of parents are not at all confident in search engines keeping their private information safe and secure and 71 percent of parents said the same about social networking sites.

Eighty-eight percent of parents said they would support a law that required online search engines and social networking services to get users' permission before they use personal information to market products.