The information has since been removed, but Chilean media reports suggest that the hacker, known as 'Anonymous Coward', managed to steal data including ID numbers, addresses, telephone numbers, emails and academic records.
Reports claim that the hacker performed the stunt to highlight poor levels of data protection in Chile.
However, despite the apparently noble intentions, security experts have slammed the hacker's actions as illegal and irresponsible.
"Chile may be on the other side of the world, but the scale of this data breach should not be ignored," said Graham Cluley, senior technology consultant at security firm Sophos.
"No matter how moral or ethical the motive, this prank was irresponsible and has left almost 40 percent of Chile's population at risk of identity theft."
Cluley added that all organisations around the world should see this as a wake-up call and ensure that all personal and sensitive information is stored securely.
This is particularly important in light of a recent pledge by the Information Commissioner's Office to impose unprecedented fines on companies that deliberately or recklessly breach data protection rules.
"Organisations around the world need to take this issue seriously and defend against these risks," said Cluley.
"Whether or not the loss results in a fine is almost irrelevant; the consequences of falling victim to such an attack can mean irreversible damage to reputation and customer confidence."
Details of six million Chileans posted online
By Staff Writers on May 14, 2008 2:55PM