Among the seven detainees, according to the news agency, are investors, a "legal person," the director, the deputy director and the workplace safety inspector of the Liuguantun mine in Tangshan, a city in north China's Hebei Province.
A Dec. 7 gas explosion at the mine killed 91 people and left 17 others missing, according to the agency.
Xinhua is reporting that an official from the country's State Administration of Work (SAWS) said the Liuguantun mine was under construction at the time of the accident and did not have a production license.
SAWS Director Li Yizhong said the mine's design deviated from government specifications and "neglected safety considerations," according to Xinhua.
Yizhong also cited "disordered management" and lack of training for miners as major causes of the accident.
Yizhong said SAWS will take "resolute measures" to try to improve mine safety, according to the news agency. China's booming economy has put a strain on coal production in the country, leading to a spate of deadly mine accidents.