Half of Americans who have a profile on social networking sites such as Facebook and MySpace are worried about their privacy, according to a new poll.

The Marist survey showed that people over 60 are the most worried about privacy, and women are more concerned than men.

We're in an era of information. Some people are concerned, reluctant and skittish about the extent of online information. There's a privacy element that some people feel is getting lost, said Dr. Lee Miringoff, director of the Marist College Institute for Public Opinion.

Privacy on social networking sites is an ongoing issue. Facebook recently changed its policies to give users more control over how much information from their profiles is public following protests from privacy watchdogs and consumers about the difficulty in changing default account settings.

It doesn't take much to increase the concern factor and when headlines start blaring about breakdowns in privacy, that goes a long way to raising people's concerns, Miringoff added.

The poll showed that 27 percent of the 1,004 people who took part in the survey were concerned about privacy on social networking websites, and a further 23 percent were very concerned.

Older Americans are more worried about privacy, he said, because social networking websites do not come as naturally to them as to younger people who have a more carefree attitude about the sites and privacy.

Overall, 43 percent of Americans said they keep in touch via social networking websites such as Facebook, MySpace and LinkedIn. Forty percent of men, and 45 percent of women, said they had a profile on a networking site.

(Reporting by Daniel Lippman; Editing by Patricia Reaney)