Those arrested are affiliated with Stand News, one of the most vocal anti-China news outlets in Hong Kong.

Six people were arrested under a colonial-era crimes ordinance.
Six people were arrested under a colonial-era crimes ordinance. (Reuters)

Hong Kong police have raided the office of an online news outlet after arresting six people for conspiracy to publish a seditious publication.

The six were arrested early on Wednesday under a colonial-era crimes ordinance for conspiracy to publish seditious content, and searches of their residences were under way, police said.

More than 200 officers took part in the search, police said. They had a warrant to seize relevant journalistic materials under a national security law enacted last year.

According to the local South China Morning Post newspaper, police arrested one current and one former editor at Stand News, as well as four former board members including singer and activist Denise Ho and former lawmaker Margaret Ng.

Later on Wednesday, Stand News said it will cease operations.

"Because of the current situation, Stand News will stop operating immediately, and stop updating its website and all social media," the outlet said in a statement on Facebook.

READ MORE: More Tiananmen monuments removed from Hong Kong universities

Crackdown on dissent

Police did not identify those who were arrested.

Early on Wednesday, Stand News posted a video on Facebook of police officers at the home of a deputy editor, Ronson Chan, where they were investigating the alleged crime. 

Chan, who is also chair of the Hong Kong Journalists Association, was not arrested but was taken away for questioning, according to the South China Morning Post.

The arrests come as authorities crack down on dissent in the semi-autonomous Chinese city. 

Police charged former newspaper publisher Jimmy Lai with sedition on Tuesday. His Apple Daily newspaper shut down after its assets were frozen.

Stand News earlier this year said it would suspend subscriptions and remove most opinion pieces and columns from its website due to the national security law. Six board members had also resigned from the company.

The Hong Kong Journalists Association urged the city's government to protect press freedom in accordance with Hong Kong's mini-constitution, the Basic Law.

“The Hong Kong Journalists Association (HKJA) is deeply concerned that the police have repeatedly arrested senior members of the media and searched the offices of news organisations containing large quantities of journalistic materials within a year,” it said in a statement.

READ MORE: G7 denounces 'erosion' of democracy in Hong Kong election

'All-out assault on freedom'

Benedict Rogers, co-founder and CEO of the non-governmental organisation Hong Kong Watch, said the arrests are “nothing short of an all-out assault on the freedom of the press in Hong Kong.”

“When a free press guaranteed by Hong Kong’s Basic Law 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,” he said.

Wednesday's arrests also followed the removal of sculptures and other artwork from university campuses last week. 

The works supported democracy and memorialised the victims of China's crackdown on democracy protesters at Beijing's Tiananmen Square in 1989.

Source: TRTWorld and agencies