Emergency teams in northern China have now recovered 63 bodies from two coal mines hit by an explosion two days ago.

State media say six miners remain missing after Saturday's blast at the Xishui coal mine (near the city of Shuozhou) in Shanxi province. The official Xinhua news agency said police have detained four owners of the mine for disregarding an order four months ago to suspend production because of safety problems.

The powerful explosion collapsed a wall between the Xishui mine, where at least 44 miners died, and the neighboring Kangjiayao mine, where 19 were killed. The Kangjiayao mine was operating legally.

China's coal mines are the deadliest in the world. Last year, explosions and other accidents killed more than 6,000 miners.