Hong Kong’s national security police have arrested the younger sister of former labour union leader Elizabeth Tang Yin-ngor and the younger brother of opposition veteran Albert Ho Chun-yan on suspicion of conspiracy to pervert the course of justice, the Post has learned.

Officers arrested Marilyn Tang Yin-lee, 63, and lawyer Frederick Ho Chun-ki, 65, on Saturday while executing a search warrant at a premise in connection with the case of Elizabeth Tang, who was released earlier in the day on HK$200,000 (US$25,480) bail, according to sources.

She was arrested on Thursday after visiting her husband, former opposition lawmaker Lee Cheuk-yan, at Stanley Prison.

One insider said Marilyn Tang and Frederick Ho were detained for questioning after officers suspected they had taken evidence related to allegations that the union leader had colluded with foreign elements in violation of the national security law.

The source added that computers, documents and mobile phones had been seized during the search.

Without naming any individuals, police said national security officers had arrested two suspects on Hong Kong Island and were holding them for questioning.

Former union leader Tang, 65, was arrested outside Stanley Prison at around midday on Thursday, taken to Stanley Police Station and then escorted to a Lai Chi Kok flat for a search of the premises.

A police insider said Tang was granted HK$200,000 bail on Saturday and must surrender her travel documents. She was detained for two days at police headquarters in Wan Chai.

Elizabeth Tang (front, right) was granted bail on Saturday.

Upon release, Tang told reporters that she did not understand why she was accused of violating the law and endangering national security. She said her work had always been related to labour rights and trade unions.

Tang had only returned to the city recently after leaving for Britain in 2021, according to another source.

“I didn’t expect to be arrested when I returned to Hong Kong – I felt baffled,” she said.

Without disclosing the person’s name, the force’s National Security Department on Saturday said it had granted bail to a 65-year-old after arresting her for suspected collusion with a foreign country or external elements to endanger national security, contravening Article 29 of the national security law.

She must report back to police on March 17.

The source said Tang was the director of an information research centre and was suspected of receiving more than HK$100 million in donations from groups in the United States, Germany and Norway since 1994 to support labour movements in Asia.

The research centre announced in 2021 that it was dissolving, around the same time as the Confederation of Trade Unions (CTU), an umbrella group her husband headed as general secretary, said it was disbanding. Marilyn Tang was a former director of the CTU Training Centre.

Elizabeth Tang holding a picture of husband Lee Cheuk-yan in 2021.

It was understood the entity was the Asia Monitor Resource Centre, where, according to the Companies Registry, Tang was a director and company secretary.

Tang left for Britain in September of that year in an apparent bid to evade law enforcement investigation, the source said.

Under Article 29 of the national security law, a person can be regarded as colluding with “a foreign country or external elements” if found to have conspired with a foreign institution or individual, or have received funding from them for various reasons.

Those reasons include to wage a war against the country, disrupt the laws or policies of the Hong Kong or central governments, engage in hostile activities against the local government or the nation, or provoke by unlawful means hatred among Hongkongers towards the central government.

Offenders face a jail term of between three to 10 years. For serious offences, the person could be subject to life imprisonment or a fixed-term jail sentence of no less than 10 years.

Tang, popularly known as “Sister Ngor”, married Lee in 1985 and they founded the CTU in 1990. The couple became prominent voices representing the local working class.

Lee, a former Labour Party legislator, was also a key leader of the now-disbanded Hong Kong Alliance in Support of Patriotic Democratic Movements of China, the group behind the city’s annual June 4 Tiananmen Square candlelight vigil.

A member of Hong Kong’s opposition camp, Lee was jailed for 20 months over his involvement in three unauthorised rallies during the anti-government protests in 2019.

The prison sentence also covers a fourth instance related to a banned June 4 vigil in 2020 to mark the anniversary of the 1989 Tiananmen Square crackdown.

Lee completed the sentence in September but remained behind bars to await trial on a national security offence, after he was also charged in 2021 with inciting subversion through his role in the alliance.