Three miners still missing after a coal pit fire that killed 25 in central China on Tuesday were unlikely to be rescued because of the high risk of a gas explosion, authorities said Thursday.

The fire broke out at 2 p.m., Tuesday, at Lisheng Coal Mine in Tanjiashan town, Xiangtan county of Xiangtan city, Hunan Province.

The gas concentration had hit 5.1 percent at 9:30 a.m. Thursday, well over the 1.5 percent limit, and was very likely to explode, said Zhang Jinbo, an official with the Publicity Department of the county's Communist Party of China Committee.

When the gas concentration reaches 1.5 percent, people, including rescuers, must be evacuated immediately, according to Coal Mine Safety Regulations.

When the accident happened Tuesday, more than 70 miners were working in the shaft. Forty-three managed to escape while at least 28 were trapped.

Five county and town level officials were removed from office Wednesday for failing to prevent the fire.

The coal mine's owner has paid funeral costs to the affected families.

Lisheng is a privately-run coal mine with 180 employees. The mine is being upgraded to double its annual output to 60,000 tonnes.