Twenty-one miners have been killed by a gas explosion in a Chinese coal mine, an official has said.

The explosion occurred in the Baiyanggou  mine in Xinjiang region's Changji prefecture, Western China on Friday.

Initially officials reported that the blast only trapped the workers.

But an official at the Xinjiang's work safety bureau said Saturday that 21 miners were confirmed dead and one was injured. The official, surnamed Wang, refused to give further details as the incident is under investigation.

Twelve miners escaped the explosion earlier on Friday.

Incidents like this are often caused by a failure to ventilate methane gas from the shaft.

China's mines are considered to be among the deadliest in the world and suffer frequent explosions, floods and cave-inse.

Safety improvements have reduced the number of deaths in recent years, but regulations are often ignored.

Source: AP