Facebook has been analyzing the emotions of teenagers and acknowledges it passed along the information to an advertiser in violation of its policies, according to published reports.

The Australian news website said it has seen internal research documents that show how people's posts on Facebook classify them as feeling "stressed," "anxious," "nervous" or other negative emotions. The report says that advertisers could use this information to target teens "when they are potentially more vulnerable," something that Facebook denies.

The report claims the leaked information shows how Facebook "has been honing the covert tools it uses to gain useful psychological insights on young Australian and New Zealanders in high school and tertiary education."