China's President Xi Jinping on Thursday warned that foreign forces attempting to bully the nation will "get their heads bashed", and hailed a "new world" created by its people as the ruling Communist Party marked the centenary of its founding.

In an hour-long address from Tiananmen Square, Xi pledged to build up China's military, committed to the "reunification" of Taiwan and said social stability would be ensured in Hong Kong while protecting China's security and sovereignty.

"The people of China are not only good at destroying the old world, they have also created a new world," said Xi, China's most powerful leader since...