Beijing has rejected the international backlash, accusing critics of "smearing" the Chinese city's judicial system.

Press advocates say the trial highlights dying press freedoms under a national security law imposed by Beijing following huge and at times violent pro-democracy protests in 2019.

Diplomats from the United States and the European Union were among those watching as the verdicts were pronounced, with Matthias Kaufmann, deputy head of the EU mission, saying he came to the court "to signal close interest in these cases".

- Britain: 'politically motivated' -

London condemned the "politically motivated prosecution" of Lai, who is a British citizen.

"Jimmy Lai has been targeted by the Chinese and Hong Kong governments for peacefully exercising his right to freedom of expression," a Foreign Office statement said, calling for his immediate release.

"The UK has repeatedly called for the National Security Law to be repealed and for an end to the prosecution of all individuals charged under it."

- China: 'punishing criminal acts'

Chinese foreign ministry spokesman Guo Jiakun said Beijing "firmly supports" Hong Kong in "punishing criminal acts that endanger national security".

"China expresses strong dissatisfaction and firm opposition to the brazen defamation and smearing of the judicial system in Hong Kong by certain countries," he told a regular press conference.

- Australia: 'deeply concerned' -

The Australian government said it was "deeply concerned by the guilty verdict".

"We have been clear in expressing our strong objections to Hong Kong authorities on the continuing broad application of national security legislation to arrest and pressure pro-democracy figures, opposition groups, media, trade unions and civil society," the foreign ministry said.

- Amnesty: 'death knell for press freedom' -

"The predictability of today's verdict does not make it any less dismaying -- the conviction of Jimmy Lai feels like the death knell for press freedom in Hong Kong, where the essential work of journalism has been rebranded as a crime," rights group Amnesty International said.

"Lai has been jailed simply because he and his Apple Daily newspaper criticised the government."

- Reporters Without Borders: 'alarming' -

Reporters Without Borders expressed outrage at the verdict, calling the charges "trumped-up".

"This unlawful conviction only demonstrates the alarming deterioration of media freedom in the territory. Make no mistake: it is not an individual who has been on trial -- it is press freedom itself, and with this verdict that has been shattered," the advocacy group said.

- Committee to Protect Journalists: 'disgraceful' -

The Committee to Protect Journalists called the verdict a "disgraceful act of persecution".

"The ruling underscores Hong Kong's utter contempt for press freedom, which is supposed to be protected under the city's mini-constitution, the Basic Law," said the organisation's Asia-Pacific director, Beh Lih Yi.

- Hong Kong Journalists Association: 'irreversible damage' -

The Hong Kong Journalists Association said the trial has long "caused irreversible damage to Hong Kong's press".

It described a media climate of self-censorship and fear "to the point where even those in power cannot accurately assess public sentiment through news".