Chinese officials are working to get tents and supplies to the five million people made homeless by the 12 May earthquake as the focus shifts from rescue to relief.
Heavy rain over southwest China are likely to interrupt relief efforts and raise the risk of reservoir breaches in earthquake-stricken areas, where tents have become the most-wanted item.
Thousands of aftershocks and a forecast of more rain compounded the difficulties for military, government and private workers trying to deliver aid and ensure millions get shelter as the focus of relief work turned inevitably from rescue to relief.
Officials say China needs up to 3 million tents to house an estimated 5 million people left homeless by May 12's 7.9-magnitude quake in Sichuan province.
Vice provincial governor Li Chengyun has appealed other parts of China and the outside world to donate tents.
Premier Wen Jiabao ordered the supply of 250,000 temporary housing units - simple steel structures normally used by construction workers - to the quake area by June 30 and the number should reach 1 million in three months, state media said.
More than 40,000 people have been confirmed dead and the government said it expected the final death toll to exceed 50,000. More than 247,000 were injured.
At a cabinet meeting yesterday, Wen warned of the threat of "secondary disasters", ordering experts to inspect dams and reservoirs on 24-hour patrols with more heavy rain forecast.
Wen said damaged dams must open floodgates to run at low or even empty water levels and the dozens of "barrier lakes" formed by numerous landslides blocking river flows must be monitored.
In Qingchuan county, where more than 2,670 people have died in the quake, troops evacuated some 9,000 residents on Tuesday after huge cracks appeared on the top of a mountain, Xinhua said.
In Beichuan, the devastation has been so complete that the government is considering abandoning the county seat and rebuilding it elsewhere, making the ravaged town a memorial, local media said. Over 8,600 people were killed in the county.
A total of 32 civilian "radioactive sources" had been buried under debris after the quake, but 30 of them had been recovered, Xinhua said. It did not give details or specify the risk.
China started three days of national mourning on Monday, with flags raised at half-mast and public entertainment suspended.
Thousands gathered in Tiananmen Square yesterday to cheer on China just 80 days before the start of the Beijing Olympics in what was supposed to be a joyful countdown to the Games.
Meanwhile, in an anti-corruption warning, the country's Communist Party's anti-corruption commission said that any action that hampers progress or wasted supplies would be swiftly dealt with.