Rescuers scrambling over the twisted metal and concrete of the devastated Chinese city of Mianzhu said on Tuesday they can still hear voices from the rubble more than 24 hours after it was hit by a quake.

With time running out for around 6000 people who remain buried here, one People's Liberation Army soldier said they remained hopeful of pulling people out alive.

"Definitely we can hear voices," said the soldier, who did not want to be named. "We will see if we can get to them."

Mianzhu, a city of around 500 000 people, is just 60 kilometres from the epicentre of the 7.9-magnitude quake that struck on Monday in southwest China's Sichuan province.

According to latest government estimates it has killed up to 12 000 people so far, and there are fears it will soar further as more details emerge.

In Mianzhu alone, just north of the provincial capital Chengdu, the death toll is at least 2000.

Li Huaqing watched anxiously as a rescue team frantically dug through the rubble of a collapsed Bank of China building where his brother was among some 30 people believed to be buried.

'My brother is in there'

"My younger brother is in there," 42-year-old Li — his eyes bloodshot from sleep deprivation — told AFP, as his sister-in-law cried next to him.

"We have not slept, we've stood here all night watching."

Thousands of people remain missing in Mianzhu. Many, like Li's brother, are thought buried under the metal and roof-sized broken slabs of concrete.

"We can still hear voices," one local policeman, working with a rescue team, confided from beside the rubble that was once the bank.

As ambulances and police cars raced past with sirens blazing, shell-shocked residents walked through their destroyed city often unsure of what to do.

Many who have been made homeless found areas of refuge in the city's parks, setting up makeshift tents with bed sheets, umbrellas and cardboard.

"Everywhere it's totally destroyed, there are rescue workers looking for people in many places," one young man said as he surveyed the devastation.

'There may be hope'

Many buildings looked as if they have been blasted apart, while others like the one where Li's brother was believed to be have been working had collapsed completely.

"Teams have been working through the night, but you can see where the roof totally collapsed, even the crane was unable to remove it," said the policeman, describing the wreckage of the bank.

"Those people (under the roof) will have been crushed, for the other people on the other side of the building where the roof is raised higher there may be hope."

Li's sister-in-law, who refused to reveal her name, said she knew that her 39-year-old husband had been inside when the earthquake hit because he would have just gone back to work after lunch.

The quake hit around 2.30 pm (0630 GMT) on Monday.

"We've searched all over, the hospitals — everywhere. He is definitely in there," she said as she held onto the arm of a woman looking for her daughter, also believed buried under the huge slabs of concrete.

Rescuers have pulled six people alive from the Bank of China wreckage since late on Monday. Local residents said 30 people remained buried under the rubble, although police said it was closer to 10.

As lines of workers struggled to remove debris piece by piece, Song Li (37) a former bank employee, looked on grimly, watching her husband who had joined in the search.

"One of my former colleagues is already dead, and another two of my colleagues are trapped in there," Song said, who until last year had worked in that building for 10 years.

"I don't know if they are alive. I hope they are."

AFP