China had detained a Chinese citizen working for Bloomberg News.
In Hong Kong, the police said on Friday that Jimmy Lai, the outspoken founder of an ardently antigovernment newspaper, had been charged under the city’s new national security law with colluding with foreign forces. Hours later, Bloomberg News disclosed that plainclothes security officials had earlier that week detained Haze Fan, a Chinese staffer in Beijing, also on potential national security violations.
Both announcements were shrouded in secrecy. The police in Hong Kong did not specify how Mr. Lai was said to have colluded with foreign countries. Chinese officials said only that Ms. Fan, who had been taken four days earlier from her apartment, was accused of “criminal activities that jeopardize national security”.