A 26-year-old waitress has become the first person to be found guilty under the colonial-era sedition law since Hong Kong’s handover to China in 1997, after confessing to inciting violence and other criminal activities via a Telegram channel she managed during 2019’s anti-government protests.

The District Court convicted Hui Pui-yee of conspiracy to commit a seditious act on her own admission on Tuesday. She also pleaded guilty to conspiracy to incite others to commit arson, in exchange for prosecutors withdrawing three other charges of a similar nature.

Prosecutors had accused Hui of taking part in a seditious plot to “incite violence” or “counsel disobedience to law or to any lawful order” by spreading hate speech and encouraging doxxing and assault against people supporting the government and police on Telegram, a messaging app popular with protesters.

She was also accused of conspiring with others on the social media platform to disseminate information about the making of petrol bombs in a bid to provoke other users to destroy properties by fire.

The offences were said to have taken place between August 12 and November 28 in 2019, when Hui and two other unknown Telegram users co-administered a channel called “boy finds dad and mum”.

The District Court convicted Hui Pui-yee of conspiracy to commit a seditious act on her own admission.

The court heard the channel, which had 60,068 subscribers on November 28 that year, had maliciously published the personal information of 1,574 people, including mainland Chinese and local government officials, lawmakers and police officers.

The group continued the illegal activity despite two injunction orders imposed by the High Court outlawing the doxxing of police officers and incitement of violence on the internet.

Among the seditious terms and phrases listed by the prosecution that were used by the defendant and her co-conspirators, were derogatory descriptions of police officers, such as “dog”, “chick” and “rogue cops”.

Other phrases deemed spiteful included “Shina” – the Japanese term for China during wartime; “blue ribbons” – used to describe people who were pro-government; and the slogan “Liberate Hong Kong; revolution of our times” – the catchphrase of the protest movement in 2019.

A forwarded post on the channel, for instance, blasted the “Communist Hong Kong government” for the “insane crackdown of dissent” in August 2019.

Senior public prosecutor Ivan Cheung Cheuk-kan said: “The channel in question published messages containing hate speech against victims who held different political beliefs, to arouse readers’ resentment towards those people.

“The channel also contained seditious allegations against the government and police … with an aim to encourage readers to target people supporting the administration of this country and the Hong Kong government, as well as committing offences against the government, police or other people or organisations.”

Hui was arrested outside her residence on November 28, 2019, after investigators identified her as one of the channel’s administrators.

She admitted under caution she had posted the personal information of government supporters on the platform, as well as calling for people to harass the victims.

Further investigations revealed that Hui had discussed with the other two administrators in two different Telegram groups about spreading information concerning the methods of producing firebombs on the channel.

Hui pleaded guilty on Tuesday after prosecutors agreed to drop two counts of conspiracy to incite and one count of incitement provided that she admitted the other two charges.

Judge Frankie Yiu Fun-che jailed Hui ahead of sentencing on April 20, pending a background report.

Offenders convicted of sedition can be punished by a fine of up to HK$5,000 and two years in prison for their first offence, while those convicted of arson can face 10 years behind bars.

The sedition law, laid out in broad terms in the 1971 Crimes Ordinance, has also been used by prosecutors to target an opposition activist and a decoration worker for openly calling for Hong Kong’s liberation before the commencement of the national security law.

Tam Tak-chi, a leading figure of localist group People Power, was slapped with 14 charges, including uttering seditious words and disorderly conduct in public, in three separate cases. The 49-year-old will seek to terminate his prosecution on the sedition charges at the District Court on Wednesday.

Separately, construction worker Chan Hau-man, 29, was charged in November with taking part in an unlawful assembly and displaying seditious publication during a protest last year against the national anthem law. He pleaded guilty to unlawful assembly on Monday, while prosecutors decided not to pursue the sedition charge. He will be sentenced on April 13.