The 20-hour exercise held Saturday and yesterday was a test of the crisis-management ability of top officials, including Premier Su Tseng-chang, the sources said.

Local television stations broadcast news footage showing President Chen Shui-bian, Vice President Annette Lu and other top officials being escorted to the Yuanshan Commander Centre on the outskirts of Taipei.

The drill followed a scenario that had the pro-independence president being assassinated by Chinese forces, with the vice president being escorted to a military camp outside Taipei to assume the duties of commander-in-chief.

Other scenarios included Parliament Speaker Wang Jin-pyng taking over as the head commander after the president, vice president and the premier were killed, the officials said.

The exercise heralded a computer-simulation war game scheduled for Monday, as part of a series of major war games code-named Operation Hankuang.

The annual operation is staged to test the combat readiness of the Taiwanese forces in the event of Chinese attack.

Military sources said the United States, an informal ally of Taiwan and major arms' supplier to the island, will send ranking officers to observe the war games.

Taiwan and China split at the end of a civil war in 1949, but Beijing still considers the island an integral part of the mainland that must be brought back to the Chinese fold, if necessary by force.

Beijing has repeatedly warned the pro-independence Chen that a formal split from China would lead to such an attack.