TOKYO, Sep 12 (Reuters) - Japan has appointed a serving government official to act as its de facto defence attache in Taiwan, four sources said, elevating security ties in a move likely to anger China, which claims the strategic, democratic island as its own.

Japan does not have any formal diplomatic representation in Taiwan and instead handles bilateral relations through the Japan-Taiwan Exchange Association in Taipei, which is chiefly staffed by reassigned foreign and trade ministry officials.

The defence attache role, however, has until now been held by a retired Japan Self Defence Force officer to avoid antagonising China.

He has been joined by an official dispatched by the defence ministry to enhance information gathering and communicate with Taiwan's military, said the sources, who asked not to be identified because of the sensitivity of the issue.

It is also "symbolic" of Japan's support for Taiwan, said one of the people who knew about the appointment. "Taiwan had been asking for an active duty defence official to fill the post," he added.

Highlighting Tokyo's nervousness about Beijing's reaction, the move was halted last year after a Japanese media report about the plan, the sources said.

Japan's defence ministry said that it would only pursue "non-governmental" ties to Taiwan, a Japanese colony from 1895 to 1945, that was within the bounds of a 1972 joint statement that recognised Beijing as the sole legitimate government of China.

Taiwan's Ministry of Foreign Affairs declined to comment when asked about the new defence attache but said it "will continue to deepen cooperation with similar-minded partners such as Japan".