The Apple Daily’s chief editorial writer was arrested at Hong Kong’s airport, local media reported, the seventh person swept up this month in a national security probe into the now-shut pro-democracy newspaper.

Fung Wai-kong was detained as he attempted to leave the city, media including the broadcaster TVB said Sunday, citing people it didn’t identify. Hong Kong police said in a statement that the city’s national security department held a 57-year-old man at Hong Kong International Airport for "conspiracy to collude with foreign forces to endanger national security,” without identifying Fung.

The move was linked to "arrest operations” on June 17 and June 23, the police said, dates that coincide with previous developments in the Apple Daily probe. "The operation is still ongoing and further arrests won’t be ruled out,” the police said.