HONG KONG--Hundreds of Hong Kong national security police raided the office of online pro-democracy media outlet Stand News on Wednesday and arrested six people for suspected "seditious publications" offences, the latest in a series of crackdowns on the media.

Stand News, set up in 2014 as a non-profit, is the most prominent remaining pro-democracy publication in Hong Kong after a national security investigation this year led to the closure of jailed tycoon Jimmy Lai's Apple Daily tabloid.

The raid raises more concerns about press freedom in the former British colony, which returned to Chinese rule in 1997 with the promise that a wide range of individual rights would be protected, media advocacy groups said.

Police said in a statement they had a warrant authorising them "to search and seize relevant journalistic materials".

"Over 200 uniformed and plain clothes police officers have been deployed," the police said.

Police also said they had arrested three men and three women, aged 34 to 73, for "conspiracy to publish seditious publications". Police did not identify them but media said the six included senior members of staff.

Ronson Chan, Stand News deputy assignment editor and the head of the Hong Kong Journalists Association (HKJA), was not among those arrested but said police confiscated his computer, mobile telephone, tablet device, press pass and bank records during an early morning search of his home.

"Stand News has always reported news professionally," Chan told reporters.

Reuters could not reach those arrested or their representatives. Chan and another person in the newsroom after police left declined to comment.

The government's Security Bureau did not immediately respond to a request for comment. Authorities have repeatedly said all prosecutions are based on evidence and had nothing to do with the profession of the people arrested.

'POLICE STATE'

Early on Wednesday, scores of police were seen milling about the lobby of the Stand News office in an industrial building in the Kwun Tong district.

Officers loaded about three dozen boxes of documents and other seized material onto a truck before leaving around mid-day. Reporters from other media were not allowed into the newsroom after the raid.

Steven Butler, Asia programme coordinator for the Committee to Protect Journalists, said the police action was an "open assault on Hong Kong’s already tattered press freedom".

Sedition is not among the offences listed under a sweeping national security law imposed by Beijing on the city in June 2020 that punishes terrorism, collusion with foreign forces, subversion and secession with possible life imprisonment.

But recent court judgements have freed authorities to use powers conferred by the new legislation to deploy previously rarely used colonial era laws, including the Crime Ordinance, which covers sedition.

Authorities say the security law has restored order after often-violent pro-democracy unrest in 2019. Critics say the legislation is a tool to quash dissent and has set the global financial hub on an authoritarian path.

"When a free press ... is labelled 'seditious', it is a symbol of the speed at which this once great open international city has descended into little more than a police state," Benedict Rogers, chief executive of the Hong Kong Watch rights group, said in a statement.

'SPEECH CRIMES'

In June, hundreds of police raided the Apple Daily, arresting executives for alleged "collusion with a foreign country". The newspaper shut down after police froze its assets.

On Tuesday, prosecutors filed an additional "seditious publications" charge against Lai and six other former Apple Daily staff.

Police had not disclosed which Apple Daily or Stand News articles they considered seditious.

The Stand News charter states that it shall be independent, autonomous and committed to safeguarding Hong Kong's core values of "democracy, human rights, rule of law and justice".

After the Apple Daily raid, Stand News said it would stop accepting donations from readers and had taken down commentaries from its platform to protect supporters, authors and editorial staff, adding that "speech crimes" had come to Hong Kong.

Stand News also said at the time that senior barrister and former democratic legislator Margaret Ng, pop singer Denise Ho and four others resigned from its board, with two founding directors, Tony Tsoi and former chief editor Chung Pui-kuen, remaining.

Media said the six people arrested on Wednesday included Ng, Ho, Chung, acting chief editor Patrick Lam and former board members Chow Tat-chi and Christine Fang.

The HKJA said in a statement it was "deeply concerned that the police have repeatedly arrested senior members of the media and searched the offices of news organizations containing large quantities of journalistic materials".