China has deployed two batteries of sophisticated surface-to-air missile launchers to a disputed island in the South China Sea.
Satellite imagery from ImageSat International showed two batteries of eight missile launchers on Woody Island, part of the contested Paracel Islands, a US news report said late Tuesday.
"Interested parties should work collaboratively to maintain peace and stability in the South China Sea region," said Taiwan Defence Ministry spokesman Major General David Lo.
"[They should] avoid any unilateral move that would increase tensions," Lo added.
A US official confirmed that the imagery showed the HQ-9 air defense system, which has a range of around 200 kilometres, Fox News reported.
The missiles appeared to have been placed on a beach some time between February 3 and February 14, the report said.
The news of the missile deployment came as US President Barack Obama met with South-East Asian leaders in California, where they called for "maritime security" and urged "non-militarization and self-restraint" by countries in the region.
Beijing claims nearly all of the South China Sea, including small islands that are hundreds of kilometres from its southern coast.
Four countries in South-East Asia have unresolved territorial disputes with China over the South China Sea, which has important shipping lanes and potential oil and other natural resources.
In January, a US warship sailed into the area of the sea containing the Paracel Islands group, and within 12 nautical miles of Zhongjian Island, or Triton Island in English.
A Chinese Defence Ministry spokesman called the move at the time "a delibrate provocation."
Woody Island is also claimed by Taiwan and Vietnam.