World Bulletin / News Desk

The death toll from a gas explosion at a coal mine in China’s northwest Ningxia Hui Autonomous Region has risen to 18 and rescue teams continue searching for two workers who remain missing after the incident -- which authorities are blaming on “illegal mining”.

State news agency Xinhua reported Wednesday that 17 bodies had been recovered from the shaft operated by Linli Coal Mining Co. Ltd. in Shizuishan City, while one miner died after being rescued.

An initial investigation reportedly showed that the blast Tuesday was a result of illegal mining, and company officials believed to hold responsibility have been placed in police custody.

Shizuishan’s vice mayor, Wu Yuguo, was quoted as telling a press conference that rescue efforts are hampered by excessive gas concentration and destruction of the mine shaft.

Chinese mines are among some of the most dangerous in the world due to lax regulations and poor operating procedures.

In recent years, the country has produced more than one-third of the world's annual coal output, but accounted for more than two-thirds of global mining deaths annually, according to Mining Technology.

In January, 11 workers were killed after a coal mine collapsed in northwest Shan Xi province, while in February a gas leak at a coal mine in northeast Jilin Province left 12 miners dead.

In March, 19 people died after a coal mine collapsed in northern Shanxi province while 129 workers were working underground.