New Delhi, July 19 -- Hong Kong tightened prison rules, allowing authorities to restrict visits, including those by certain lawyers and religious personnel, on national security grounds, in the latest expansion of its stringent control.

Under the new rules, effective Friday, magistrates can issue warrants on application by correctional service officers to bar exchanges between specific legal representatives and persons in custody if the judges believe such connections could harm national security or cause bodily harm to any person, among other reasons.

The department can also restrict certain visits, including those made by specific chaplains, for purposes such as maintaining national security, preventing crime and facilitating inmate r...