Australian journalist Cheng Lei was jailed in China for almost three years after breaking an embargo following a briefing by Chinese officials.
The Melbourne mother of two was arrested in August 2020 and held in a Chinese jail for two years and 11 months.
She was accused of national security-related offences but the circumstances surrounding her detainment have not been made public until now.
An embargo is an agreement between a journalist and other parties, such as governments or companies, to hold off publishing information until an agreed time.
The former anchor for the state-run China Global Television Network broke the embargo by just a few minutes, she revealed in her first interview since her release and return to Melbourne last week.
"Essentially you broke an embargo," Sky News reporter Annalise Neilsen put to Ms Lei.
"Yes," Ms Lei responded.
She said in China that was considered a "big sin".
"You have hurt the motherland, that the state's authority has been eroded because of you," she explained.
"And what seems innocuous to us here, I'm sure it's not limited to embargoes, but many other things are not in China, especially I'm given to understand the gambit of state security is widening."
The 48-year-old broke down as she spoke about seeing her children and mother for the first time on Wednesday after arriving back home.
"We just all screamed and my mum wept and I just held onto her," she said.
Ms Lei went to a Vietnamese restaurant with her family and had a celebratory champagne before heading to the Queen Victoria Market during her first few days of freedom.
She was held in isolation for about six months and allowed 30-minute-long consulate visits while in prison.
Ms Lei said it would take time to adjust back to normal life as she was still afraid of something happening, such as her children being taken away.
"I keep expecting people to drop out of the sky and arrest me," she said.
Last week, Prime Minister Anthony Albanese said Ms Cheng's return was not part of a deal struck with Beijing and her release followed the completion of China's judicial process.
The federal government continues to advocate for the release of Australian writer and activist Yang Hengjun, whose health is deteriorating.
He has been detained since January 2019 and continues to await a verdict in his case with his judgment deferred.
