Many people lost all their possessions in the earthquake
Chinese regulators have warned that any corrupt practices linked to relief supplies for the Sichuan earthquake will be severely punished.
Officials are working to get tents and supplies to the five million people made homeless by the 12 May quake.
The official death toll is now more than 41,000, and another 32,000 people are still missing.
There was some good news on Wednesday when a woman was reportedly rescued from a tunnel of a hydropower plant.
The state news agency Xinhua said she had been trapped in the tunnel in Hongbai for nine days.
She has been air-lifted to hospital, suffering from multiple fractures, but she is expected to survive.
But aid workers hold out little hope of finding many more survivors.
Both domestic and international aid has been flowing into the earthquake zone, with supply planes landing from countries including the US, Russia and Singapore.
But China says more tents are desperately needed to provide temporary shelter for families.
Up to Tuesday 20 May:
145 confirmed aftershocks above level 4, 23 above level 5, biggest 6.1
34,000 medical staff in quake zone
Nearly 280,000 tents, 480,000 quilts and 1.7 million jackets sent
6bn Chinese yuan ($860m, £440m) received in donations, from China and abroad
Drinking water for 7m people restored
Source: Chinese government
Bulldozers have been levelling ground so that more camps can be set up, reporters at the scene said.
In one tent city in Mianzhu, a 52-year-old man told the French news agency AFP that he had nothing.
"We don't know where we're going to find money to rebuild our village," Ma Jingsuan said. "We're entirely dependent on the government."
On Tuesday, Chinese Premier Wen Jiabao pledged to send 250,000 temporary housing units to the region by the end of June, and one million within three months.
In a circular, the Communist Party's graft watchdog told local agencies to deal "swiftly and severely" with any official corruption linked to relief work, Xinhua news agency reported.
The source, destination and quantity of relief supplies should be made public, it said, and police should crack down on any fraudulent collection of donations for earthquake victims.
There have already been reports of scam text messages calling for donations to help survivors.
In the earthquake zone, many residents whose homes are still standing have been sleeping outside because of continued fear of aftershocks.
Rain has also been falling, compounding their misery. On Tuesday, Mr Wen ordered patrols to constantly monitor all dams as the bad weather continued.
Thousands of residents have also been evacuated from an area in Qingchuan county where large cracks have appeared in the top of a mountain, Xinhua said.