Tabletop exercises are a tool strategists use to game out how real-world scenarios may unfold, testing how organisations will react and coordinate against a simulated threat.

A national security official speaking on condition of anonymity told AFP the Thursday morning exercise, led by the president's office, involved 19 central ministries, local governments and NGOs.

"It aims at bolstering Taiwan's whole-of-society defence resilience in the face of authoritarian expansion by China and other countries as they continue to challenge the international order," they said.

While Taiwan regards itself as a sovereign nation, China claims the self-ruled island as part of its territory and has not renounced using force to back its rhetoric.

China has intensified military and political pressure on the island in recent years and staged three rounds of major military drills since Taiwanese President Lai Ching-te came to power in May.

The official said the simulation tested Taiwan's response to "high-intensity grey zone operations" by an adversary -- actions which fall short of an act of war but which are "on the brink of conflict".

The security official said the scenario used to test Taiwan's readiness were theoretical drills by China this year targeting a strategic chain of islands encompassing Taiwan, Japan and parts of the Philippines and Indonesia.

Taipei accuses Beijing of ramping up so-called "grey zone" harassment by sending warplanes and naval vessels around the island of Taiwan on a nearly daily basis.

In October, Taiwan said it detected a record 153 Chinese military aircraft in a 25-hour period, after Beijing held large-scale drills which it said served as a "stern warning" to "Taiwan independence forces".