Beijing: China said Thursday that Chinese-Australian author and democracy advocate Yang Hengjun was detained on national security grounds, becoming the latest Western citizen to face such accusations from Beijing.

Australia demanded that Yang - a former Chinese diplomat - be treated "fairly and transparently" and complained that Beijing had waited four days, instead of three as required, to notify Canberra about his detention. Yang was detained shortly after he made a rare return to China from the United States last week.