The March 12 explosion left 21 people dead and four missing at the Machang coal mine in Shuicheng county.

Nearly 300 people participated in search and rescue efforts, state news agency Xinhua said, adding that an investigation was underway.

The explosion is the third in the area in the past five months. Another 13 miners died in an explosion in Panxian county on January 18, while a coal gas burst two months earlier killed 23 at Xiangshui mine.

A rock outburst also occurred in northeast China last week, trapping 20 workers at the Junde coal mine in the Heilongjiang province.

Contact was established with 16 of the miners, who were rescued about 10pm Friday. Rescuers are still trying to make contact with the four remaining miners.

According to recent economic figures from the Chinese National Bureau of Statistics, last year’s coal mine death toll was down 33.75% on 2011, but its safety record still remains one of the worst in the world.

Government efforts to reduce hazardous mines have resulted in the closure of more than 9000 small coal mines since 2006.

In September, Chinese authorities pledged to shut down 20,000 illegal and unsafe mines by 2015 following a string of deadly gas explosions and collapses.