ZHOUQU, China (Reuters) - Wails of grief echoed through a northwest Chinese town half-smothered by a landslide two days ago, as relatives washed mud-caked bodies pulled from ruins and the official death toll mounted.

The count of dead from the disaster in Zhouqu, in a narrow valley in Gansu province, jumped from 137 earlier on Monday evening to 337, according to a local official cited by the official Xinhua news agency.

That toll is sure to grow, with another 1,148 residents counted as missing and possibly buried under the mud and rocks that engulfed much of the town.

Rescuers and locals with just shovels, hoes and rope spread over more than 2 km of devastated land to burrow into homes encased in mud left by floodwater that swept down from the slopes around Zhouqu in Gansu late on Saturday night.

“There are around 20 of my family members under there,” said Zou Jianglian, who had rushed back from a job in nearby Wuwei town to search for her mother, father, younger brother and other relatives lost since the disaster.

Nearly 1,500 people in other parts of the country have already died in landslides and flooding caused by months of torrential rains, the ministry of Civil Affairs said.

Relatives of the missing in Zhouqu trekked into the disaster zone, some helping with excavation efforts while others watched in desperate hope.

Hopes rose when a 74-year-old woman was found alive on Monday morning, the official Xinhua agency reported. She had been trapped in a fourth floor apartment rather than the low-rise buildings almost obliterated by rocks and sludge.

Chinese Premier Wen Jiabao visited the town, still two thirds underwater, for a second day and hollered at rescuers and survivors not to give up, state television news showed.

In the worst hit-village not a single structure was intact, although rescuers said they had not given up hope.

“There are probably eight people buried under this site,” said a soldier, Luo Siyuan, who was helping dig for survivors in Zhouqu town.

“They might not be able to survive after such a long time, but we will not give up on them. It may be a good way to show our respect for the dead.”

Engineers were also blasting a barrier of rocks and mud in an effort to drain an unstable lake upstream from the town of 40,000 residents, when landslides also choked up the Bailong River.

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With more rains forecast for this week, there may be fresh disasters if the unsecured natural dam bursts, although thousands of people downstream have already been evacuated as a precaution.

HOMES, LIVES SWEPT AWAY

The mass of mud and rocks buried at least 300 low-rise homes, state media reported, while images showed multi-storey concrete buildings toppled or with chunks gouged out.

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Vital supplies are now running low, with food, water and tents stuck in vehicles several hundred meters from the site.

“We need more food and water. We are now out of power and water supplies,” said Yuan Manhong, a 24-year-old survivor.

China has deployed the resources of its powerful central government to battle a string of natural disasters in recent years -- flooding, quakes and landslides -- winning popular support for both the military and leadership.

Experts said the landslide, which carried mud and rubble over five kilometers (three miles), could have been caused by earth made vulnerable to heavy rain by a recent drought and the 2008 Sichuan earthquake that may have loosened the mountainside. (Writing by Emma Graham-Harrison; Additional reporting by Chris Buckley in Beijing; Editing by Sanjeev Miglani)