The Hong Kong legislator Albert Chan is removed from the chamber after heckling the territory’s chief executive over his failure to speak out on the missing booksellers (Isaac Lawrence)

AN INTERNAL Chinese Communist party document has tied the recent disappearances of dissident book publishers, including a British citizen, to a party order to unleash its security services on opponents in exile.

It describes measures to “exterminate” banned books and magazines at their source, identifying 14 publishing houses and 21 publications in Hong Kong as targets.

Five men connected to a Hong Kong publisher, Mighty Current Media, have vanished, including Lee Bo, a British passport holder who is one of its owners. All are believed to be in custody in China.

Lee vanished from a book warehouse in Hong Kong on December 30 and there is no record of him crossing the border.

Early today, Hong Kong police said Lee’s wife, Sophie Choi, had met