Eleven people, aged 18 to 72, have been arrested on suspicion of helping 12 democracy activists flee Hong Kong by boat last year

Hong Kong police have arrested 11 people under the national security law for allegedly helping 12 pro-democracy activists accused of attempting to flee the city by boat for Taiwan last year, local media and activists reported on Thursday.

Police arrested eight men and three women aged 18 to 72 for “assisting offenders”, according to the South China Morning Post, which cited unnamed sources.

Authorities threaten to revoke licences of pair who assisted group of 12 that tried to flee to Taiwan

Chinese authorities have threatened to end the careers of two lawyers who assisted 12 activists who tried to flee Hong Kong for Taiwan last August, 10 of whom were given jail terms by a Chinese court last week.

Ren Quanniu – who also represented the Wuhan citizen journalist Zhang Zhan – and Lu Siwei received notices from local departments of justice on Monday that authorities intended to revoke their licences and they had three days to arrange for a defence hearing.

Group’s trial on the mainland lasted just one day and was held with few public witnesses

Ten people who tried to flee Hong Kong for Taiwan have been sentenced in a Chinese court to up to three years in jail, while two minors will be returned home without charge.

On Wednesday the Yantian people’s court ordered the group to serve varying sentences of between seven months and three years in jail. Of the two people charged with organising the illegal border crossing, one was sentenced to three years and fined RMB20,000 (£2,260), and the other to two years and fined RMB15,000.

Prosecution of 10 Hong Kongers detained in mainland China after allegedly attempting to flee to Taiwan also began on Monday

Zhang Zhan, a 37-year-old former lawyer and citizen journalist who was arrested in May while reporting from Wuhan, has been sentenced to four years in jail.

Zhang was arrested for “picking quarrels and provoking trouble” – an accusation commonly used against dissidents, activists and journalists – with her video and blog reports from the Wuhan lockdown. Last month she was charged with disseminating false information.