HONG KONG (Reuters) - Ten of 12 Hong Kong people captured by China at sea as they tried to flee by boat four months ago will go on trial in the mainland city of Shenzhen on Monday, supporters said on Friday. The case has attracted great interest in Hong Kong and abroad as a rare instance of the Beijing authorities arresting people trying to leave the financial hub at a time of growing concern about the prospects for the city’s high degree of autonomy. The families had asked this week for 20 days’ notice to allow them to attend the trial, given a 14-day COVID-19 quarantine upon entering mainland China. Instead, the families of seven detainees were notified of the trial date by government-appointed lawyers, a support group said. “Obviously (the Chinese authorities) are rushing during the Christmas period so as to minimise international backlash,” said Beatrice Li, sister of detainee Andy Li. Beijing’s Hong Kong and Macau Affairs Office did not immediately respond to a request for comment. Twelve Hong Kongers were intercepted by the Chinese coastguard on Aug. 23 on a boat believed to be bound for Taiwan. Two underage suspects will undergo private hearings on a separate date, Chinese authorities said earlier this month. All were facing charges in Hong Kong linked to anti-government protests in the former British colony, including rioting and violation of a national security law Beijing imposed on the city in June. In their mainland trial, they face charges of illegally crossing the border and organising an illegal crossing, which could carry sentences of up to seven years. The Hong Kong government has said the defendants must face justice on the mainland before returning to Hong Kong, where they are expected to be further investigated for the suspected protest-related crimes.