In China's eyes all three Taiwan presidential candidates are separatists, the front-runner to be the island's next leader said on Wednesday in a fractious joint televised address with the other contenders.

The Jan. 13 presidential and parliamentary elections will define Chinese-claimed Taiwan's ties with Beijing, and are happening as China steps up military activities around the island to assert its sovereignty claims.

China has rebuked current Vice President Lai Ching-te, the ruling Democratic Progressive Party's (DPP) presidential candidate and leading in the polls, as a dangerous separatist, and portrayed the vote as a choice between war and peace.