Nine miners were killed and four injured in an underground coalmine explosion in northeast China.

While seven miners were killed in the mine tunnel in Diaobingshan city of Liaoning Province on Friday immediately after the explosion, two others succumbed to injuries, the state media reported on Saturday.

The four injured, suffering mainly from bruises and bone fractures, are under medical treatment, the Xinhua news agency quoted head of Teifa Coal Industry Department Sun Shikui as saying.

According to Liaoning Provincial Coal Mine Safety Inspection Bureau, the coal mine, in a disused tunnel, started to spontaneously combust when 13 miners were reinforcing it. The leaked gas caught fire and caused an explosion.