The kidnapping and detention of a group of Hong Kong booksellers is of no concern to the city’s government, its new leader has said. Five booksellers associated with Hong Kong-based Mighty Current publishing were detained two years ago by Chinese police, with two of the men spirited across borders by plainclothes agents. The case sparked international condemnation and protests in Hong Kong, and added to fears that the city’s autonomy was eroding. But Carrie Lam, who is to be sworn in as Hong Kong’s chief executive on 1 July, said the matter was purely a concern for mainland authorities.