Hong Kong’s privacy watchdog has arrested a 27-year-old woman on suspicion of doxxing after she allegedly posted the personal details of her friend’s ex-boyfriend on social media.

The Office of the Privacy Commissioner for Personal Data on Wednesday said it arrested the woman following an investigation. She was later granted bail.

According to the investigation, the woman became acquainted with the victim through his ex-girlfriend in February 2022. That July, the man broke off the relationship and in the same month, a post containing his personal details with negative comments about him was found on a social media platform.

The Office of the Privacy Commissioner for Personal Data conducted an investigation into the incident.

The personal data included the victim’s Chinese name, company and residential addresses, mobile phone number, social media account and photos, according to the commissioner.

The woman is suspected of breaching section 64(3A) of the Personal Data (Privacy) Ordinance, a clause related to doxxing, by allegedly disclosing the man’s personal details without his consent. A person who commits an offence under the section is liable on conviction to a fine of HK$100,000 (US$12,740) and imprisonment for two years.

The watchdog said the investigation was ongoing.

The privacy commissioner has arrested 21 people since the new anti-doxxing law took effect in October 2021, and laid charges in nine of the cases, with others still under investigation.

“[The office] also referred 40 cases, which involved the more serious doxxing offence or other criminal offences, to the police,” it said.

The office warned that doxxing was a serious crime, with an offender being liable on conviction to a fine of up to HK$1 million and five years in prison.

“[The privacy law] applies equally to the online world,” the watchdog said. “To avoid breaking the law, members of the public should think twice before publishing or forwarding any doxxing messages on the internet or social media platforms.”

Last month, a court sentenced a 36-year-old online trader to two months in jail but suspended it for two years after she pleaded guilty to 14 charges of doxxing. The court found she had posted the personal data of her supplier online, including details about the victim’s husband after their business relationship turned sour over a money dispute.

It was the second sentencing in a case initiated by the watchdog since Hong Kong amended its privacy law to criminalise doxxing.

The first person to be sentenced for doxxing was a 27-year-old man who was jailed for eight months last December after he pleaded guilty to seven charges. He had posted the personal details of his ex-girlfriend online after they broke up.

According to documents the watchdog gave to the Legislative Council in February, the office received 3,848 complaints last year of which about 46 per cent, or 1,764, were related to doxxing.