The death toll from a coal mine blast in north China's Shanxi Province rose to 31 as rescuers retrieved three more bodies early Wednesday.

Rescuers found one body at 4:00 AM and another two at 7:00 AM under the main shaft of the Anxin Coal Mining Co. Ltd mine in Xiaoyi City.

The three bodies were pulled out.

An explosion occurred in the mine at about 11:00 AM on Friday when 58 miners were working underground. Fifteen managed to escape and another nine were saved by rescuers.

As of 7:00 AM on Wednesday, rescuers had recovered the bodies of 31 miners and were still searching for the remaining three.

Illegal homemade explosives, which were concealed in the colliery tunnel, ignited on their own and triggered the blast, said Shanxi Vice Governor Zhang Jianmin on Tuesday.

Zhao Tiechui, the State Administration of Coal Mine Safety's director, said an initial analysis showed Anxin had many problems. These ranged from the use of explosives unsuitable for mining to excessive production.

The company also illegally mined unapproved areas and had poor ventilation facilities.

Police detained four people -- the mine's chief and legal representative Tian Yun, a deputy chief and two workers in charge of blasting operations.

(Xinhua News Agency June 18, 2008)