Rescuers trying to enter the accident site.

Twenty-six hours after 18 miners were trapped by a coal mine blast on Wednesday, rescuers still could not enter the mine in Lianyuan city of central China's Hunan Province, because of high gas density, officials said.

"Chances of their survival were slim," said Shi Jinchu, vice director of the city's production safety bureau.

More than 800 tonnes of coal blocked a 120-meters section of the seam, which hampered rescue work, said Yan Yinchu, deputy director of the provincial production safety bureau.

He said rescuers needed to reduce the gas density in the mine before entering the seam.

The blast occurred at 3:15 p.m. as 32 miners were working, and 14 managed to escape.

Rescuers are trying to contact the trapped miners.

The township-owned Guaziyan colliery opened in 1997. It has a designed annual capacity of 30,000 tonnes but has sought to double that level.

All coal mines in Lianyuan city halted production for safety checks and an investigation into the cause of the incident was launched.

(Xinhua News Agency December 19, 2008)