Hundreds of employees of the Eastern Cape health department have been issued with final warnings aft.
The accident happened on Thursday morning in Fengcheng, in Jiangxi province, during work on a cooling tower for a coal-fired power plant. A tower crane collapsed, triggering the collapse of the entire construction platform.
Xinhua said the nine included the chairman of Hebei Yineng Tower Engineering, whose family name they gave as Zhang.
State media has said the company was in charge of the building project.
A company official reached by telephone declined comment.
Xinhua said the nine were suspected of "major liability" in the accident and would face criminal charges, but gave no other details other than that the probe was continuing.
State media said last week 13 people had been taken into custody in connection with the disaster. Xinhua did not say what had happened to the other four.
Deadly accidents are relatively common at industrial sites in China, where anger over lax standards is growing. Three decades of swift economic growth have been marred by incidents ranging from mining disasters to factory fires.
China has vowed to improve its poor safety record.
President Xi Jinping has said authorities would learn the lessons paid for with blood after chemical blasts in the port city of Tianjin killed more than 170 people last year.
Shortly after those explosions, Yang Dongliang was removed from his post as director of the State Administration of Work Safety and later charged with corruption.