Rescuers, racing against time to save 19 trapped coal miners in south China, on Monday halted their efforts due to high levels of toxic gas in the mine shaft, state media said.

After carbon monoxide gushed out of the mine at 2:45 am, the rescue command centre ordered the rescuers to retreat to the platform of the main shaft, said Ye Fangyong, an expert from the command centre. Ye said other toxic gas in the mine is over the safety level.

Rescuers said the location of the trapped miners has been identified, but their condition was unclear. As of this morning the command centre was still trying to identify the source of the carbon monoxide and find a solution to recommence the rescue operation, the official Xinhua news agency reported. Ye said the rescue will resume as soon as possible.

The collapse occurred on Saturday in the suburbs of Heshan City in Guangxi Zhuang Autonomous Region. Initial investigations indicate that the collapse was caused by continuous heavy rains.

Forty nine of 71 miners managed to escape when the coal mine collapsed, and rescuers have retrieved three bodies of the dead miners.