For decades, Hong Kong’s movie industry has enthralled global audiences with balletic shoot-em-ups, epic martial-arts fantasies, chopsocky comedies and shadow-drenched romances. Now, under orders from Beijing, local officials will scrutinize such works with an eye toward safeguarding the People’s Republic of China.

The city’s government Friday said it would begin blocking the distribution of films that are deemed to undermine national security, marking the official arrival of mainland Chinese-style censorship in one of Asia’s most celebrated filmmaking hubs.

The new guidelines, which apply to both domestically produced and foreign films, come as a sharp slap to the artistic spirit of Hong Kong, where government-protected freedoms of expression and an irreverent local culture had imbued the city with a cultural vibrancy that set it apart from mainland megacities.