A gossip column threatening to "out" actress Rebel Wilson was "likely to cause substantial offence and distress", the Australian Press Council has found.
Earlier this month, the Australian star labelled Sydney Morning Herald journalist Andrew Hornery's attempt to reveal her relationship with fashion designer Ramona Agruma "grubby behaviour".
His Private Sydney column, titled Rebel Starts Spreading The News was published in June.
While the journalist had hoped to break the story of Wilson's same-sex relationship, he instead was forced to comment on her own announcement after the Bridesmaids star revealed the news on Instagram, the day before his column was due to be published.
Along with a picture of herself and Agruma together, Wilson announced her relationship to the world, writing: "I thought I was searching for a Disney Prince... but maybe what I really needed all this time was a Disney Princess #loveislove."
Hornery's column the following day described how Wilson had "ignored" his email requests for comment and instead had opted to "gazump" him.
His column attracted a global backlash from celebrities and LGBT charities alike, criticising his attempt to out the actress.
That column was later removed, and replaced with an apology from Hornery, in which he said he had "mishandled" the story, and understood why his email to Wilson "had been seen as a threat".
Admitting the tone of his resulting column was "off", he said it was not the newspaper's "business to 'out' people", adding, "that is not what we set out to do". He also said as a gay man, he was "well aware of how deeply discrimination hurts".
Within his apology, he included the content of his original email to Wilson's management team, telling her he had "several sources" confirming her relationship status, and had "enough details to publish". He had given her two days to respond.
He said this was his deadline, rather than an ultimatum.
The Australian Press Council, which is the principal body with responsibility for responding to complaints about Australian newspapers, magazines and digital outlet, published its ruling on the Herald's website on Saturday.
The media watchdog wrote: "The tenor of the publication's communications with Ms Wilson concerning a deeply personal matter, and the associated commentary on a matter which had no apparent connection to her public activities, intruded on her reasonable expectations of privacy.
"The council considers that, taken collectively, the article's reference to 'outing' same-sex celebrity couples, its reference to giving Ms Wilson two days to respond to information concerning her relationship, and its forthright criticism of her for not responding, was likely to cause substantial offence and distress."
They found there was not enough public interest to justify the intrusion, and that the paper had broken two of the council's general principles in publishing the column.
Earlier this month, Wilson told The Australian newspaper the "hurry" to reveal the news of her relationship publicly had meant they had been yet to tell some family members they were a couple.
Wilson is set to star in her first dramatic role in indie film The Almond And The Seahorse, which will be out in UK cinemas later this year.