China's top safety administration urged coal mines to finish construction of their emergency relief systems by the end of June to provide safety shelters to miners.

Previously, the deadline was 2015.

According to a statement issued by the State Administration of Work Safety and the State Administration of Coal Mine Safety on Wednesday, authorities have specific requirements for the safety shelters' ventilation and oxygen supply systems.

The statement also urged coal mines to train their workers on how to use the systems, and maintain them well.

Nearly 2,000 people in China died in coal mine accidents in 2011, the first time in 10 years that the number of casualties was brought down to less than 2,000.