French, US and other navy ships have long visited Hong Kong harbour
China has rejected a requested port call in Hong Kong by Japan's navy, Japanese media have reported.
The Asahi Daily quoted Japanese and Chinese officials as saying the visit was blocked because of "sensitive issues" and "technical details".
China's state-run China Daily said there was good reason to block the requested naval visit.
It cited trips to Japan by the Dalai Lama and Uighur activist Rebiya Kadeer - considered separatists by Beijing.
China says Mrs Kadeer and the Dalai Lama want to split China by fomenting unrest from exile abroad.
Japan's Asahi Daily newspaper quoted unnamed Japanese officials saying the request for two training vessels and one destroyer to make a stop in Hong Kong was rejected on 12 August because of "sensitive issues".
Chinese foreign ministry spokesman Qin Gang was quoted by the Asahi Daily as saying: "Due to technical reasons, it is not convenient for China to receive the Japanese Self-Defence Forces warships in Hong Kong."
The ships are on a 13-nation tour and had hoped to visit Hong Kong later this month or early in September.
Chinese officials protested to Japan over the visit to Tokyo last month of activist Rebiya Kadeer.
China has accused Mrs Kadeer of instigating ethnic riots in Xinjiang province last month that resulted in 192 deaths, according to official Chinese accounts.
The China Daily reported that a Japanese diplomat who declined to be named had said Tokyo and Beijing were still negotiating the visit.
It also quoted a Hong Kong Chinese-language newspaper's applause of any decision to block Japan's port call request.
The first Japanese warship to visit China since World War II moored at a naval base in Zhanjiang, Guangdong province last year, drawing national attention because of Japan's past invasion of China.
It is not the first time China has refused access to Hong Kong for a foreign navy. US warships were turned away in 2007 because of, a foreign ministry official said, US arms sales to Taiwan and Washington's award of a medal to the Dalai Lama had harmed relations.