Despite age restrictions on some social media sites, the number of parents who would allow children 10-12 years old to have a Facebook or MySpace account has doubled in a year, a new survey showed.

Seventeen percent of parents questioned in the poll said they had no problem with a pre-teen child using a social media site, compared to just eight percent a year ago.

And 11 percent of parents admitted to using social media sites on behalf of a young child or infant, according to the online survey of about 1,000 adults by Liberty Mutual's Responsibility Project.

More and more parents are allowing their children to have a Facebook account or to have more online activity at younger and younger ages. said Janet Taylor.

The clinical instructor of psychiatry at Columbia University at Hospital in New York described the findings as a sign of the times.

It's not alarming. I think it means we need to be aware of what is going on and how to best utilize social media, she added in an interview.

Most parents think that children under 18 should not be able to keep their account to themselves and a third monitor their usage. Forty four percent also limit the time spent on the Internet or texting.

Facebook, which has 500 million active users, was the most popular social network among adults in the poll. Nearly 90 percent used it frequently, followed at a very distant second by the professional website LinkedIn with 6 percent, Twitter and MySpace.

Although only three percent of people questioned said they used the microblogging site Twitter frequently, they had definite ideas about what was acceptable and what was not.

Nearly two-thirds thought it was unacceptable for the staff of celebrities and CEOs to ghost-tweet for them and 46 percent didn't think celebrities should use Twitter to argue with each other.

Twenty seven percent also did not agree with CEOs tweeting about their company.

Most Twitter users follow their friends and celebrities and tweet about their daily activities or current events. Only four percent tweeted about politicians or a religious leader, while 11 percent tweeted about their own achievements and 8 percent used it to criticize other people.

When questioned about cyber-bullying, most parents said they thought it was their responsibility to resolve the situation if their child was a victim and 63 percent thought teachers and schools should be doing more to stop it.