Taipei: On Monday, Taiwan's new defence minister said his government would not recognise any air defence identification zone (ADIZ) which Beijing may proclaim in the disputed South China Sea.
Hong Kong's South China Morning Post newspaper has cited Chinese army sources as saying Beijing was considering declaring a zone.
Any such move, said US Secretary of State John Kerry yesterday, would be "a provocative and destabilising act".
China unilaterally established an ADIZ in the East China Sea in December 2013, demanding all aircraft submit flight plans when traversing the zone which covers islands disputed with Tokyo and also claimed by Taipei.
That move angered the United States, Japan and South Korea as well as Taiwan.
China claims nearly all of the South China Sea despite competing partial claims by several Southeast Asian neighbours as well as Taiwan. It has built artificial islands in the area suitable for military use.
Taiwan's Defence Minister Feng Shih-kuan told parliament his ministry would not recognise any ADIZ in the South China Sea should Beijing proclaim one.
"We'll take a concrete step to show that it is unacceptable," Feng said without giving details.
Ties between Taipei and Beijing have turned frosty since Tsai Ing-wen took office as the island's president. Beijing distrusts her Democratic Progressive Party, which has traditionally favoured formal independence for the island.
China still insists Taiwan is part of its territory awaiting reunification, by force if necessary, even though the two have been ruled separately since 1949.