China's Communist Party has sacked the assistant chairman of the country's securities regulator, state media agency Xinhua reported on Tuesday, days after it was announced he was the subject of a graft probe.

Zhang Yujun is by far the highest-ranked securities official investigated. [Photo/China Daily]

Zhang Yujun was under investigation for suspected "serious violation of discipline", the country's graft watchdog reported on Sept 16, using the euphemism it employs for corruption.

Zhang is the first China Securities Regulatory Commission (CSRC) official to come under investigation amid stock market turmoil, which started in June.