CHINA-FUNDED companies in Hongkong are being banned from advertising in newspapers and political magazines seen as ''unfriendly'' to Beijing. A local New China News Agency official yesterday said granting preferential treatment to ''friendly newspapers and magazines'' was justified. ''We understand that different newspapers and magazines have their own political stance, but we hope the Hongkong media will co-operate with the Chinese Government,'' the official said. According to an internal circular issued by the Hongkong-Macau Regional Office of the Bank of China on 7 August 1991, published by Ming Pao yesterday, subsidiaries of the Bank of China Group were not to place adverts in eight Chinese-language newspapers and eleven magazines. The blacklisted newspapers were the Hongkong Economic Times, Hongkong Daily News, Express Daily, Sing Tao Jih Pao, Sing Tao Wan Pao, Hongkong Economic Journal, Financial News and the now disbanded pro-Taiwan Hongkong Times. The magazines were Pai Shing, The Nineties, Cheng Ming, Open Magazine, The Contemporary, The Trend, News File, The Wave, South and North Poles, Newsdom Weekly and Ming Pao Monthly.