Hong Kong's national security police arrested 11 people in dawn raids on Thursday, including a veteran human rights lawyer, on suspicion of helping a group of activists make a failed bid to flee the city by speedboat.
"Eleven people were arrested by the national security department for 'conspiracy to assist offenders'," a senior police source told AFP.
The officer confirmed those arrested were suspected of aiding 12 Hong Kong pro-democracy activists caught last August by Chinese coastguards as they tried to flee by boat to Taiwan.
Those on board were facing charges in Hong Kong for crimes linked to huge and often violent democracy protests that convulsed the finance hub in 2019.
The arrests come a week after national security police detained more than 50 of the city's most prominent democracy activists for subversion, one of the new crimes listed in a sweeping national security law that Beijing imposed on the city last year.
Among those detained on Thursday was Daniel Wong, a veteran human rights lawyer and an outspoken supporter of Hong Kong's democracy movement.
"National security police arrived at my home around 6.10 am and I do not know at the moment which police station they will take me to," Wong wrote on his Facebook page.
The 71-year-old is also the founder of a restaurant in Taipei which hires and helps Hong Kongers who have fled to the democratic island.
Willis Ho, a former student leader, confirmed her mother was among those arrested.
Last month a Chinese court jailed 10 of the 12 fugitives for up to three years for "organising and participating in an illegal border crossing".
Two teenagers were returned to Hong Kong to face charges including attempted arson and possession of offensive weapons.
It is not the first time people have been arrested on suspicion of trying to help the group escape Hong Kong.
In October, nine people were detained by the city's new national security unit and later granted bail
The national security law mandates up to life imprisonment for any offence Beijing views as "secession, subversion, collusion with foreign forces and terrorism".
At least 90 people have been arrested since the law's enactment, including US-born human rights lawyer John Clancey, prominent activist Joshua Wong and pro-democracy media mogul Jimmy Lai.