A fatal blaze at a foot massage parlor in eastern China was caused by an electrical fault in a steam room, China's top work safety watchdog said on Wednesday.

Flames engulfed Zuxintang Foot Massage in Tiantai, Zhejiang province, at 5:26 pm on Feb 5, killing 18 people and injuring 18 others.

A preliminary investigation showed the fire started after the steam room's heating system malfunctioned, causing rising temperatures that ignited some flammable objects, according to the State Administration of Work Safety.

"It was an accident caused by human error," Su Jie, a spokeswoman for the watchdog, said at a news conference on Wednesday.

The management of the parlor－which occupied the first and second floors of a six-story building in a downtown community－and the relevant local government department should take the blame, Su said.

However, she added that an investigation into the case is ongoing.

Police in Tiantai detained four people in connection with the incident on Feb 7, local media reported.

At the news conference on Wednesday, the State Administration of Coal Mine Safety also provided an update on its investigation into an explosion at Zubao Coal Mine in Lianyuan, Hunan province, on Feb 14 that killed six people and left four others missing.

Yang Fu, deputy director of the agency, said the authorities are looking into whether the mine covered up the death of a miner in the accident, which happened when 29 people were underground.

He said rescuers are trying to find the missing workers and that local authorities have formed a work group to investigate the cause of the blast.

"Investigators have found traces of a coal dust explosion in the shaft after entering the mine several times," Yang said, adding that the watchdog will punish those responsible if any cover-up is discovered. Police have detained a manager at the mine, surnamed Liu, who is suspected of covering up the miner's death, Xinhua News Agency reported.

Three officials are also under investigation, including two vice-mayors of Lianyuan and the local production safety chief, according to the report.