HONG KONG—Hong Kong police have arrested pro-democracy activists Joshua Wong and Tam Tak-chi for violating Hong Kong’s pro-Beijing National Security Law, increasing the total number of arrests using the Beijing-backed law from 53 to 55. Both were in police custody at the time of the arrest on Thursday. Wong, former secretary-general of local pro-democracy party Demosistō, has been serving a sentence in Shek Pik Prison. Tam, a former radio presenter nicknamed “fast beat” and vice chairman of the pro-democracy party People Power, has been detained at the Lai Chi Kok Reception Center since September last year. Although Wong and Tam were in custody, Hong Kong police stated that they were arrested again due to their running in the 2020 primary elections for the pan-democracy camp. Since the two were already serving a sentence in detention, there was no need for bail or reporting to a police station. Both Wong and …