A survey of children's web habits shows that "sex" and "porn" are among the top 10 most-searched terms.

The study logged webpage visits through security firm Symantec's OnlineFamily.Norton, a web-monitoring service for parents.

Video website YouTube topped the list, as did search engines Google and Yahoo, along with social networking sites Facebook and MySpace.

The survey scanned 3.5 million searches between February 2008 and July 2009.

TOP CHILDREN'S SEARCH TERMS 1. YouTube 2. Google 3. Facebook 4. Sex 5. MySpace 6. Porn 7. Yahoo 8. Michael Jackson 9. Fred (YouTube star) 10. eBay

In a statement Symantec's internet safety advocate, Marian Merritt, said that with the service, "parents can stay in the loop on what their kids are doing online".

"It also helps identify 'teachable moments' when parents should be talking with their kids about appropriate online behaviour and other issues in their kids' online lives."

One unexpected term in the top 10 is "Fred" - the internet name for a young performer whose YouTube channel is a favourite among young web users.

Terms such as "sex" and "porn" often figure in strongly when searches are ranked by popularity - with a notable exception being a survey in 2008 showing that they did not reach the top ten among Google users in China.

Ms Merritt said that the findings of the recent survey are not all that shocking.

"Any of us who have been teenagers are not surprised kids look for information about sex," Ms Merritt told AFP news agency.

"I think we have all gotten over our shock that the Internet has porn."