Chinese state media say a gas explosion at a coal mine has killed 28 people in central China.

The official Xinhua news agency said Sunday one miner remains trapped following the blast Saturday in Hengyang city in Hunan province.

Authorities say six miners have survived the explosion.

China's mines, many of which operate illegally, are among the world's deadliest, largely due to lax security measures.

Official data show more than 2,400 people were killed in Chinese mining accidents last year, and labor rights groups say many more deaths may have gone unreported.