China poured in more troops into the earthquake-battered southwest Sichuan province on Wednesday to speed up rescue operations as state media reported that only 2,300 people were believed to have survived out of 10,000 living in a town at the epicentre of the disaster.

At least 500 bodies have been pulled out after the emergency workers reached Wenchuan county, the epicentre of the 7.8 magnitude quake that struck on Monday.

The report from the official Xinhua News Agency did not say if the 7,700 believed dead in Yingxiu town of Wenchuan county were in addition to an already reported death toll of more than 12,000.

Around 20,000 soldiers and armed police had landed in the quake-hit areas and another 30,000 were en route by air, road and rail and on foot, Xinhua said. The navy has also summoned 2,500 men from the Marine Corps, it said.

As rescuers dug through rubble of collapsed homes, schools and hospitals, fears also rose that the toll could go up. At least 18,000 people were either buried in debris or reported missing in Sichuan province, which alone has accounted for 12,012 deaths and 26,206 injured.

It was a moment of relief in an atmosphere of grief when rescuers pulled some 500 people alive out of the debris in Mianzhu county where more than 3,000 people have been killed by the quake. Some 20,000 people in three villages were still out of reach. 

Rescue workers mounted a gigantic search effort using cranes and manpower looking for survivors, but were hampered by rain in some areas of the hilly region.

"Transportation, electricity, communication and water supply should be resumed to ensure that the disaster relief work goes on successfully, and resuming transportation is the key," Premier Wen Jiabao said as he moved from one affected place to another overseeing relief works.

In Mianzhu, close to the epicentre, buildings of a steam turbine plant was destroyed with more than 500 workers and their family members missing or buried in the rubble, a company official said. "The other workers have been looking for the missing colleagues by digging out the collapsed buildings with shovels and even hands," the official added.

"People escaped from the buildings, but were only devoured by the landslides," said a survivor in Beichuan county where the killer quake flattened 80 per cent of the buildings.

The toll in the county is estimated up to 5,000, but local residents fear it could be 7,000 to 8,000, Xinhua said.

Offers of aid have come from several countries, including the US and the European Union.

US President George W Bush [Images] spoke over phone on Tuesday night to his Chinese counterpart Hu Jintao and conveyed that Washington was willing to provide "any possible assistance" for disaster relief.