In a bid to tighten censorship, the State Press and Publication Administration last night banned Sino-overseas joint ventures and Sino-overseas co-operative businesses from the distribution or wholesale of publications. The ban covers political documents, writings of leaders, books, newspapers, periodicals, audio and visual products and online electronic publications, Xinhua said. The ban comes as online bookstores and online electronic publications become increasingly popular on the mainland. Leaders are also concerned about the leaking of 'state secrets' as the Internet helps to spread information quickly. Authorities have maintained a tight grip on the media and publication industries. The latest regulation on the control of publications says only state-authorised distributors with a minimum capital of 10 million yuan (HK$9.3 million) will be allowed to engage in national distribution. State-owned or collective enterprises with capital of more than 500,000 yuan will be allowed to conduct regional distribution after seeking approval. Businesses or individuals with more than 100,000 yuan in funds can sell publications at the retail level after taking special training courses. 'Sino-overseas joint ventures and Sino-foreign co-operative businesses can only conduct publication retail business,' the regulation says. They have to seek prior approval from provincial press and publication administrations as well as file their applications with the State Press and Publication Administration. The administration said violators would be punished and illegal publications seized. The administration also ordered a cut in the number of newspaper organisations in the next six months.