Tokyo has appointed a serving government official to act as its de facto defense attache in Taiwan, four sources said, elevating security ties in a move likely to anger Beijing.

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

He has been joined by an official dispatched by the defense ministry to enhance information gathering and communicate with Taiwan's military.

It is also "symbolic" of Japan's support for Taiwan, said one of those who know about the appointment. "Taiwan had been asking for an active duty defense 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.

Taiwan's Ministry of Foreign Affairs said it "will continue to deepen cooperation with similar-minded partners such as Japan."

Taiwan Affairs spokesman Chen Binhua said Beijing opposed "any form of official exchanges between countries with which China has established diplomatic relations and China's Taiwan region".

"China urges the Japanese side to draw lessons from history, abide by the one-China principle and be prudent in its words and actions on the Taiwan issue," Chen said.

Beijing's expanding military presence around the island, only 100 kilometers from Japan, has unsettled Tokyo. It worries about becoming embroiled in any conflict that could also threaten nearby sea lanes that supply Japan with most of its oil.

A Taiwanese warship keeps track of China's Shandong aircraft carrier yesterday.

Japan ups ante for Taiwan