BEIJING — China’s ruling Communist Party expelled the former chief of Interpol on Wednesday, accusing him of abusing his power to finance an extravagant lifestyle and committing “serious” violations of the law.

The disappearance of the former Interpol chief, Meng Hongwei, during a trip to China last fall drew global attention and highlighted the perils of being on the wrong side of China’s opaque, highly politicized legal system.

The Chinese authorities later said he had been placed under investigation, but the move damaged China’s reputation and raised doubts about President Xi Jinping’s efforts to expand China’s global presence.

Mr. Meng, 65, the first Chinese citizen to lead Interpol, has not been heard from since.

The harsh punishment of Mr. Meng is probably an effort by Mr. Xi, China’s most powerful leader since Mao, to signal that political loyalty is paramount, experts said.