The Australian Broadcasting Corporation (ABC) has confirmed that a website related to the 2010 TV program Making Australia Happy was breached with 49,500 audience usernames and hashed versions of passwords leaked.
A hacker going by the Twitter handle of Phr0zenMyst claimed ownership of the attack and said it was a response to the recent appearance on ABC's Lateline program of right-wing Dutch politician Geert Wilders.
"The aim of the hack was to hurt ABC for allowing Wilders to spread hate, apologies for any harm caused to others," tweeted PhrOzenMyst yesterday.
As soon as the company was made aware of this breach, the website was shut down.
An ABC spokeswoman confirmed that it has now written to the 49,500 people that were affected.
"The ABC has sincerely apologised for the incident and assured the users of the Making Australia Happy site that immediate action has been taken to contain the breach and a review of the safeguards is underway," she said.
The spokeswoman added that some reports about the hack were incorrect.
"There was a survey on the site that was designed to measure how happy people are. The only information that was hacked is the information users provided to register for the website. Responses that users gave to the survey have not been exposed."
Follow Hamish Barwick on Twitter: @HamishBarwick