The Chinese state news agency says 21 miners were killed in a mine explosion in southwestern China last week.

The accident happened Thursday at a small mine in Panzhihua, in Sichuan province. Xinhua news agency says 10 miners survived the disaster.

It says a preliminary investigation found the blast was caused by poor management practices. It did not explain the delay in reporting the blast.

China has the deadliest mines in the world, despite government efforts to improve safety. More than 1,000 miners have been killed this year. Mine producers ignore safety regulations to fulfill soaring energy demands brought on by China's booming economy.

Some information for this report provided by AP and Reuters.