Chinese President Xi Jinping pledged on Thursday to complete "reunification" with self-ruled Taiwan and vowed to "smash" any attempts at formal independence, drawing a stern rebuke from Taipei, which lambasted the Communist Party as a dictatorship.

China, which considers democratically-ruled Taiwan its own territory, has stepped up efforts under Xi to assert its sovereignty claims, including regular flights by fighter jets and bombers close to the island.

"Solving the Taiwan question and realizing the complete reunification of the motherland are the unswerving historical tasks of the Chinese Communist Party and the common aspiration of all Chinese people," Xi said in a speech on the 100th birthday of the ruling Communist Party.