Rescuers hope to contact 12 trapped miners late Thursday by drilling through to a flooded coal mine where 31 miners have been trapped since Monday in north China's Inner Mongolia Autonomous Region.

Rescue teams were forced to revise their plans to contact 12 of the 31 trapped workers Wednesday and find a new drilling site after one drill missed the target area.

By 2:20 p.m. Thursday, the fastest drill had reached 159 meters underground, 43 meters above the area where the 12 miners were believed to be, said Wu Qingfeng, deputy chief engineer of? Wuhai Energy Co. Ltd. at Luotuoshan Coal Mine in Wuhai City.

"If everything goes well, it can reach the 12 miners in four or five hours," said Wu.

The third of the eight drills at the site was previous the fastest but missed the target which was supposed to be 202 meters underground where 12 miners were trapped, Wu said.

Altogether eight drills have been working at the site since the pit was flooded on Monday.

Rescuers were previously expected to drill through to the mine by 4 p.m. Wednesday.

The drilled holes would provide air, food and a means of communication for the miners who are believed to have a slim chance of survival.

Twelve of them are believed to be trapped at a mining platform 202 meters underground, at least 10 meters above the surface of the flood water.

The other 19 people, believed to be at another platform 287 meters underground, might have drowned, Wu said Wednesday.

An estimated 100,000 cubic meters of water poured into the pit of Luotuoshan Coal Mine early Monday.

Of the 77 people working in the pit, one is known to have died and 45 are confirmed to have survived.

Most of the miners are migrants from Ningxia Hui Autonomous Region and the provinces of Shaanxi, Shanxi and Henan.

Luotuoshan Coal Mine is owned by Wuhai Energy Co. Ltd. and its parent company is Shenhua Group Corp. Ltd., one of China's leading mining firms.