Rescuers have begun shoring up the collapsed main shaft of a north China coalmine in a bid to reach nine trapped miners.

The 40-strong rescue team was forced to work in six shifts because of the confined space, said an official with the government of Chengde county, in Chengde City, Hebei Province.

Two miners died and nine were trapped underground following a gas explosion Thursday in the Dadi Coal Mine.

Eighteen people were working in the shaft when the accident occurred at about 1 p.m., but only seven escaped.

Local authorities are discussing compensation for the families of the victims.

The Hebei provincial work safety administration has begun an investigation into the cause of the accident.

The mine has an annual production capacity of 40,000 tonnes. Its production licence expired in June 2006, and production was suspended.