Children are using the Internet to watch YouTube videos, connect with friends on social network sites and look up "sex" and "porn," according to a study of the top Web searches by youngsters.

Computer security firm Symantec Corp identified the top 100 searches conducted between February and July through its family safety service OnlineFamily.Norton, which monitors children's and teenager's Internet use.

It found the most popular search term was for YouTube, the video sharing website owned by Google, with Internet star, Fred Figglehorn, a fictional character whose YouTube videos are popular with children, coming ninth in the top searches.

The search engine Google was the second most popular search term and Yahoo came seventh, while social network site Facebook ranked third and MySpace came fifth in the list.

But the words "sex" and "porn" also made it into the top 10, ranked numbers four and six respectively.

Other popular search terms included Michael Jackson, eBay, Wikipedia, Miley Cyrus who plays Hannah Montana in the hit Disney series, Taylor Swift, Webkinz, Club Penguin, and the Black Eyed Peas' song "Boom Boom Pow."

California-based Symantec's Internet safety advocate Marian Merritt said the list showed that parents needed to be aware what their children were doing online.

"It also helps identify "teachable moments" when parents should be talking with their kids about appropriate online behavior and other issues in their kids' online lives," she said in a statement.

The list was compiled after Symantec studied 3.5 million searches made by the OnlineFamily.Norton which lets parents see what children are searching and who they are talking to on instant messaging and what social networks they are using.