Its most recent action was the launch of the “Rise From the Ashes” crowdfunding campaign on May 27, which is still ongoing. As of Wednesday, about 18,000 people had donated more than US$1.69 million, more than 96.4 per cent of its US$1.75 million goal.

The anti-government protest group had vowed to use the funds to support a range of initiatives including international lobbying for the coming two years, as well as a video production and two print advertisements in the United States or Britain if the funding target was met.

Despite arrest, Hong Kong media mogul Jimmy Lai says he would ‘still have gone down same path’

On Wednesday, Lai received a hero’s welcome from staff and supporters when he returned to his Apple Daily office within hours of being released on police bail, pledging to keep the tabloid-style newspaper running.

Beijing’s national security office in Hong Kong chose the same day to make its first public statement since it began operating in the city, backing the operation to arrest Lai, 71.

Police detained the media mogul, his 39-year-old son Ian Lai Yiu-yan, and Royston Chow Tat-kuen, 62, the chief operating officer and chief financial officer of the newspaper’s parent company, Next Digital, on suspicion of collusion with foreign forces to endanger national security in a high-profile operation on Monday.

Former student activist Agnes Chow Ting and two others accused of the same crime were also picked up in another swoop the same day. The other two activists arrested were Wilson Li Chung-chak, a freelancer for ITV and former member of the disbanded student activist group Scholarism, and Andy Li, a member of a group created to monitor last November’s district council elections.

One source said Agnes Chow and the other two activists were the suspected “key members” in Hong Kong behind the online group, while the media tycoon – together with son Ian and Royston Chow – allegedly funnelled the group hundreds of thousands of dollars via overseas bank accounts in different transactions over the past six weeks.

“So far, we have identified two to three overseas-based members of the group who are now in Europe and the US to help lobby other countries to sanction Hong Kong,” he said.

He said Lai’s top aide, Mark Simon, US-based Hong Kong Democracy Council managing director Samuel Chu, and one more activist were wanted in the case.

“We are also looking into who has continued to offer financial support to the group after the new law was enacted,” another source said. “Their donation will constitute an offence under the new legislation if they are knowingly aware of the group’s illegal acts and continue to fund them.”

The donations for SWHK’s crowdfunding scheme surged after Lai and others were released on Wednesday at midnight. A total of 312 people had donated throughout the day as of 7pm, mostly in small amounts ranging from US$10 to US$500. Only 17 donations were recorded on Monday and nine on Tuesday.

SWHK, an anonymous group which emerged in the early days of the anti-government protests, has mounted several international lobbying efforts over the past year, including running an advertising campaign in seven media outlets in Britain and co-drafting a report that listed officials and pro-Beijing politicians to be sanctioned for eroding human rights in the city.

The group also facilitated the creation of a new All-Party Parliamentary Group (APPG) on Hong Kong – an informal group of members of the British parliament – last November, with the aim to “promote democracy and the rule of law, and to defend human rights” in the city.

The APPG on Hong Kong is co-chaired by Baroness Natalie Bennett and Alistair Carmichael MP.

A check of the UK parliament’s register found that the secretariat service of APPG was provided by political communication firm Whitehouse Consultancy, which was funded by SWHK. The firm declared it had twice received from SWHK about £36,000 (US$47,088) for its work with APPG on Hong Kong, on November 5 and January 8.

In March this year, the APPG on Hong Kong launched an inquiry into the alleged violation of human rights and humanitarian principles by the city’s police force during the anti-government protests that erupted last year.

Neither the Hong Kong activist team nor the British parliamentary group attempted to conceal their collaboration. The former made it clear that part of the donation it received from members of the public would be used to support the secretariat operation of the APPG on Hong Kong. The latter went on to produce a report of the so-called inquiry on August 4, which stated it was supported by the Whitehouse Consultancy, which was in turn “remunerated for that work” by SWHK.

The report slammed what it deemed excessive police violence in Hong Kong and urged Britain to punish Chief Executive Carrie Lam Cheng Yuet-ngor and the commissioner of police with sanctions.

The sources said the arrests of the six were not prompted by the APPG’s August 4 report, but police would look into the allegation that the online group had sponsored it.

In a defiant statement on Tuesday, SWHK said all of its donations had been parked in foreign banks and the group would continue to organise and help with foreign actions over Hong Kong.

“You think we will be frightened after the arbitrary arrests? We will only fight back harder,” it pledged.

Chris Whitehouse, founder of the Whitehouse Consultancy, said: “We back pro-democracy campaigners 100 per cent in their fight for freedom … they can continue to count upon our support, no matter what reaction that provokes from the Chinese Communist Party.”

What is ‘I want laam caau’?: crowdfund group linked to Hong Kong arrest of Jimmy Lai

Legal scholar Eric Cheung Tat-ming, of the University of Hong Kong, said whether the donors of a crowdfunding project had committed an offence would hinge on knowledge of how their money would be spent.

“If the campaign has stated clearly that it would call for overseas sanctions, then that would constitute a breach of the national security law. When a person donates and supports the drive, he or she would also breach the law,” he said.

While the national security law was not retroactive in nature, Cheung said, the ongoing crowdfunding campaign – or the group’s acts after June 30, if any – could give police grounds to investigate them. But the past acts could only be regarded as background and police could not prosecute the suspects solely for what they did before the law’s imposition, he added.

Additional reporting by Kanis Leung