China ordered fresh waves of helicopters and aid to earthquake-devastated areas as the sheer magnitude of caring for tens of thousands of homeless survivors threatened to overwhelm relief efforts.

The Communist Party leadership told officials to "ensure social stability" as Monday's 7.9 magnitude quake in southwestern Sichuan province spawned rumours of chemical spills, fears that dams could burst and scenes of collective grief. The official death toll estimate from Monday's quake stood at 14,866. But as search teams sift, often bare-handed, through towns turned to rubble, that number is likely to balloon. And the strains from tens of thousands of homeless are growing.

But a new threat emerged as officials warned of uncertain risks from numerous dams that were damaged in the quake zone. "Especially in Sichuan province, there are many dams, damage from the quake is extensive and the hazards are unclear," Minister for Water Resources Chen Lei said in the speech that was posted on the ministry Web site (www.mwr.gov.cn) on Thursday.

Chinese state media have said troops rushed to repair cracks in the Zipingpu Dam. Investors, meanwhile, were upbeat, with many Sichuan-area shares outperforming the main index's rise of 0.54 percent due in part to expectations of demand from rescue and reconstruction efforts. In Dujiangyan and other hard-hit cities and towns, many residents have had to sleep outside or in makeshift shelters, fearing more tremors and building collapses. "In one minute the city we know flew away.

I never dreamt it could happen," said He Lixia, a teacher in Dujiangyan. Wang Yujie, a teacher whose school withstood the quake, said getting more water was now residents' most immediate need. "There is enough food but not enough water, we have only had bottled mineral water the past few days, nothing to cook with," she said as she queued beside a water truck. In some villages near the badly hit area of Beichuan, angry residents complained they had had little to eat and were forced to drink contaminated water to keep themselves alive. Unhygienic waste was also a growing problem as temporary toilets failed to keep up with demand.

The ruling Chinese Communist Party's Standing Committee met late on Wednesday to assess the calamity that has thrown a shadow over preparations for the Beijing Olympics in August. The government ordered fresh waves of troops to be dispatched, raising the total to some 130,000 committed to the effort, and 100 more helicopters to help send rescuers and supplies to areas blocked by buckled roads, state media said.

"As long as there is a glimmer of hope, spare no efforts in rescuing," the Party leadership ordered, according to Xinhua. But the waves of rescuers appear to be hampered by lack of specialised equipment. In the Sichuan town of Hanwang, huge cranes were working at some sites to clear demolished buildings, but at other sites residents picked through the rubble by hand. Into the fourth day since the quake, hopes of pulling survivors from crushed homes, schools and factories dimmed. In Dujiangyan, rescuers wrapped corpses dragged from the rubble in tarpaulins, and after allowing relatives to briefly mourn, sped them to morgues.

They were so busy that a notice outside one collapsed school, where locals said 300 children died, asked parents to search for missing children in shifts.

"Because there is a heavy work load at the morgue we have arranged first for the parents of years 1, 2, 3 students to go and then organise for the parents of year 4, 5, 6 students," it said.

Offers of help were pouring in. Blood banks in Beijing reached saturation point, with at least 3,300 people in the capital donated blood in a single day on Tuesday. China also overlooked its hostility toward Taiwan, the self-governing island it sees as a breakaway province, to allow in chartered flights full of supplies. A Japanese relief team was also headed to Sichuan, China's Foreign Ministry said.

There were signs in some towns that more officials were arriving to organise the relief efforts, but many places were still a chaotic mess of makeshift tent cities.

The disaster area is home to China's chief nuclear weapons research lab in Mianyang, as well as several secretive atomic sites, but no nuclear power stations.

The China Nuclear Engineering and Construction Corp reported that several of its facilities in Sichuan were damaged by the quake, with six staff killed. The report on its Web site (www.cnecc.com) did not describe the facilities or mention any radiation leaks. A Western expert with knowledge of the Mianyang lab said it was not likely the facilities were put at serious risk.He requested anonymity.

Landslides had blocked the flow of two rivers in northern Qingchuan county, forming a huge lake in the region. "The rising water could cause the mountains to collapse. We desperately need geological experts to carry out tests and fix a rescue plan," Xinhua quoted Li Hao, the Communist Party chief of the county, as saying. Premier Wen Jiabao, a geologist himself, has made emotional appeals from the disaster zone urging on workers and comforting orphaned children and was set to travel on Thursday to Qingchuan. The quake was the worst to hit China since 1976 when up to 300,000 died.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.