Hong Kong police have arrested nine people accused of helping pro-democracy activists flee the former British colony for Taiwan.

The group allegedly supplied a speedboat for the 12 anti-Beijing demonstrators to make their escape attempt, as they feared prosecution by authorities there.

Read more: Hong Kong residents leave, if they can

"Their roles include ownership of the boat, financial backing, providing accommodation before the trip, transportation to the pier and arranging their lives after arriving in Taiwan," a police spokesperson was quoted as saying by the Agence France-Presse news agency on Saturday.

Police also seized the equivalent of €53,000 ($63,000) in Hong Kong currency, computers, mobile phones and financial documents relating to the boat journey.

China's coast guard picked up the 12 activists in late August, although Hong Kong officers insist that they played no role in those arrests.

Families of the detainees have said they are being held without charge at a detention center in the Chinese city of Shenzhen, just over the border from Hong Kong.

Hong Kong rocked by anti-government protests

Taiwan, a self-ruled island that China regards as a breakaway province, regularly offers political asylum to dissidents.

Hong Kong has been rocked by anti-government protests for more than a year, initially sparked by a draft extradition law that would allow Hong Kongers to face trial in mainland China.

Some of the nine suspects arrested on Saturday had previously been detained during those demonstrations.

Hong Kong's pro-Beijing administration imposed a new security law in June that critics say curtails freedom of speech and the right to protest.

Read more: Hong Kong security law: What does China really intend?

Britain handed the territory back to China in 1997, but both sides agreed a treaty that was meant to protect basic democratic rights, such as an independent judiciary and freedom of assembly.

Dominic Raab, the British foreign secretary, said in July that Beijing should "respect Hong Kong’s autonomy and respect China's own international obligations."

jf/aw (AP, AFP, dpa)