The two accidents happened Thursday in Dashucun coal mine and Friday noon in the Tao'er coal mine respectively, in which ten miners have been confirmed dead and 18 others are still missing, said rescuers, adding that the survival chances for the trapped are very slim.

The gas density in both coal mines is still beyond safety limits and the explosion caused a large amount of coal powder, said a spokesman for the rescuing headquarters.

Rescuers have to use mechanic fans to dissipate gas in the shaft and then sprinkle water on the powder to prevent the particles from floating in air before they can search for the trapped miners.

They are also required not to use any mechanical equipments to avoid hurting the trapped workers.

The Dashucun coal mine is among the country's highest gas density coal mines. Rescuers have to stop clearing the debris immediately when the gas density is detected to exceed the safe level, a spokesman with the coal mine said.

By 17:00 pm yesterday, 113.4 tons of coal powder has been cleared from the coal mine.

The government of Hebei Province has decided to install gas monitoring system to all coal mines this year to prevent gas blast and make use of the gas resources.