HONG KONG — When the Foreign Correspondents’ Club of Hong Kong decided in late July to invite an obscure political activist to speak at the elegant 19th-century building that is its home, there was a vague sense among its board that the move might upset some people.

Their guest, Andy Chan, was the leader of a fledgling political party with at most a few dozen members but a provocative goal — the secession of Hong Kong from China — and the local authorities were preparing to outlaw the party as a threat to public order and national security.

Still, few expected the reverberations that followed: Beijing demanded that the club cancel the speech. Hong Kong expelled a prominent journalist after the club refused. And the backlash raised questions about the city’s future as a haven where rule of law and civil rights are better protected than elsewhere in Asia.

“I would say it is the biggest mistake the Hong Kong government has ever made,” said Fu Hualing, a law professor at the University of Hong Kong, of the decision to expel Victor Mallet, the Asia news editor of The Financial Times. “It has a huge impact. I don’t know whether it was intended or not, but it has been felt everywhere.”