HONG KONG — The Hong Kong police said on Saturday that they had arrested nine people accused of helping a group of protesters, who were later intercepted by the mainland Chinese authorities, flee the city in August by speedboat.
The arrests seemed intended to send a message to anyone who might consider helping other antigovernment protesters escape Hong Kong, where anxiety about Beijing’s tightening grip has intensified since the Communist Party imposed a sweeping national security law on the Chinese territory in June.
The nine people arrested on Saturday are accused of funding the protesters’ planned escape to Taiwan and offering them shelter and a ride to a remote pier in Hong Kong, a police spokesman, Ho Chun-tung, said.
At least one of the nine is accused of supplying a boat, Mr. Ho said.
The 12 protesters who tried to escape were barred from leaving Hong Kong, the police said, and have been under investigation over their participation in the large-scale demonstrations that gripped the territory last year. Some face serious charges, and they are expected to face trial in the mainland for illegally crossing the border with Hong Kong.
“We suspect that these nine individuals helped the 12 fugitives avoid hearings in the courts, or they have prevented them from being arrested by the police,” Mr. Ho said.
Most of the four men and five women arrested on Saturday were friends of the captured protesters, he said. Among the group were assistants to former lawmakers, an office worker, a chef and a music teacher. The police did not release their names but said their ages ranged from 27 to 72.
They each face up to 10 years in prison if convicted.
Last year’s demonstrations evolved into the most serious challenge to the Communist Party’s rule in decades. The protests targeted a proposed extradition law, since abandoned, that would have exposed the city’s residents to trial on the mainland, where courts are controlled by the party.
As many as 200 Hong Kong protesters are believed to have fled to Taiwan over the past year. Going there by sea has become increasingly risky, and smugglers who once plied the route are now unwilling to participate.
As of late September, the 12 captured protesters, aged 18 to 33, were being held in the Chinese city of Shenzhen, at a detention center near the border with Hong Kong.
The charge that they face of illegally crossing the boundary with Hong Kong carries a maximum penalty of up to one year in prison, or seven years if they are found to have organized such an effort.
Pro-democracy lawmakers and activists in Hong Kong have pushed for the mainland government to return the detainees to the territory. But Beijing has called demands for their release “absurd,” and an official at China’s foreign ministry has described the protesters as separatists.
The activists’ have been barred from seeing human rights lawyers and were told that the attorneys at their trial would be appointed by the mainland authorities, according to their relatives.
The Hong Kong news media have reported that the territory’s police force deployed aircraft during the early morning hours of the Aug. 23 escape attempt, suggesting that the local police played a role in ensnaring the protesters.
Mr. Ho denied that the local police had coordinated with the mainland authorities. “Their arrests within the mainland have nothing to do with Hong Kong police,” he said.