HONG KONG – The Chinese government has blocked the sale of books written by certain Hong Kong and Taiwan authors who have expressed support for the pro-democracy protests currently taking place in the streets of Hong Kong.

Among those newly outlawed is Giddens Ko, the prolific Taiwanese writer who has recently become a leading light in the Greater Chinese film industry.

China’s State Administration of Press Publication, Radio, Film and Television on Saturday gave a verbal order to publishers to cease sales of the specified authors, according to multiple Hong Kong and Taiwan media reports. The order did not give a specific reason for their banning.

Among those banned are Chinese-American historian Yu Ying-shih, Hong Kong critic and TV host Leung Man-tao, Peking University law professor Zhang Qianfang and columnist Xu Zhiyuan. In the cases of Yu and Ko, the order went further and required the immediate removal of their books from shelves.

The banning appears to be a form of punishment of the authors, as the previously published books make no commentary on the current Hong Kong political problems.

The Chinese government has moved in other ways to minimize coverage within China of the Hong Kong situation. These include limiting access to Hong Kong newspaper websites, blocking Instagram, and preventing certain web search terms from showing any results.

Some bookstores in Shenzhen and Guangzhou were slow to comply with the new order, while others held a brief promotion, suggesting that the books by Ko and Xu would soon be unavailable.

Ko’s manager was reported Monday to have been unable to confirm the ban, but Ko himself used his Facebook page to tell fans not to worry about him. Ko has been a prominent supporter of Taiwan’s ‘Sunflower Movement’ which opposes further trade ties between Taiwan and Mainland China. And in recent weeks he shaved his head in support of the ‘Occupy Central’ movement currently blocking the streets of Hong Kong.

Ko was director of “You Are The Apple of My Eye” a nostalgic, school days drama that was a hit in Taiwan, Hong Kong and mainland China, and was screenwriter and producer of another recent hit “Café, Waiting, Love.”

In March it emerged that Alibaba Pictures Group, the movie arm of e-commerce giant Alibaba, had struck a deal with Star Ritz Productions. The deal spans the production of five feature films to be written and/or directed by Ko. It remains unclear whether the deal covers his upcoming “Kung Fu.”