Jailed Hong Kong media tycoon Jimmy Lai has been arrested again, on suspicion of assisting one of 12 fugitives China captured at sea last year, his Apple Daily tabloid and Oriental Daily said on Wednesday, without citing a source.

Lai, detained while awaiting a bail hearing on Thursday, has been charged with colluding with foreign forces under a sweeping national security law that Beijing imposed on Hong Kong last year.

The fugitives could face potential charges in Hong Kong over mass anti-government protests in 2019, with Andy Li, whom the papers identified as the person Lai was suspected of helping, being investigated for suspected national security crimes.

Neither newspaper gave further details. It was unclear if the national security legislation extends to the assistance Lai is suspected to have given Li.

Police did not immediately respond to a request to comment.

The Chinese coast guard captured the 12 fugitives in August as they tried to flee Hong Kong in a boat believed to be bound for Taiwan. All were held virtually incommunicado in a mainland China prison until a trial late in December.

Ten were jailed for terms ranging from seven months to three years for illegally crossing the border or organising the crossing, while two minors were sent back to Hong Kong.

Lai was already the most high-profile person to be charged under the new security law, for statements made on July 30 and Aug. 18, in which prosecutors say he requested foreign interference in Hong Kong's affairs.

He was arrested in an August raid by about 200 police officers on the newsroom of his Apple Daily, known for its feisty and critical coverage of China and Hong Kong.

Beijing imposed the new law on the former British colony last June, after months of pro-democracy protests, to target anything China that considers subversion, secession, terrorism or collusion with foreign forces.

Punishment under the law can range up to life in prison.

Critics say it is aimed at crushing dissent and erodes freedoms in the semi-autonomous financial hub. Supporters say it restores stability after months of unrest.