South Korea is a leading chip maker and the industry ministry would continue to monitor the situation, since it could not rule out the possibility that China might extend the scope of its export controls to other materials, said Young J. Joo, deputy minister for industrial policy.

"We are monitoring the situation in key countries such as the U.S. and Japan and will make utmost efforts to prepare measures to deal with even unlikely situations," the deputy minister said.

China did not control an absolute amount of germanium in the world as it did with rare earths, the official said.

The ministry will continue to support the development of alternative materials and import channels, he added.

The Korea Mine Rehabilitation and Mineral Resources Corporation (KOMIR) had about 40 days stockpile of gallium that local industry could use, a government source with knowledge of the matter said, adding there were other sources of germanium.

Taiwan, home to the world's largest contract chipmaker Taiwan Semiconductor Manufacturing Co Ltd (TSMC), expects the short-term impact of the controls to not be big, Economy Minister Wang Mei-hua told reporters in Taipei.

China both produces and exports large amounts of the rare elements gallium and germanium but in unrefined form, which is refined overseas in countries such as the U.S. and Japan, and then imported by Taiwan imports, Wang added.

"But what impact on the international markets long-term controls will have, we will pay attention to, and pay close attention to follow up price fluctuations or supply issues," she said.

(Reporting by Joyce Lee and Ben Blanchard; Additional reporting by Hyunsu Yim in Seoul; Editing by Ed Davies and Louise Heavens)

By Joyce Lee and Ben Blanchard