China has evacuated over 197,000 people from an area at risk of flooding by landslide-blocked rivers near the epicentre of this month's earthquake in Sichuan province, Xinhua news agency said on Saturday.
Shouting "evacuate! evacuate!", police with loudspeakers fanned through Youxian on the outskirts of Mianyang city, which was devastated by the May 12 quake.
The town was almost deserted, with shops shuttered and apartment buildings silent, as officials searched for stragglers in makeshift tarpaulin shelters erected by refugees on the banks of the Fu River.
Residents of Youxian were ordered to move to higher ground in the hills around the town as hundreds of soldiers dug dams and channels upstream in an effort to reduce pressure on the Fu river and prevent it from overflowing, which could inundate the area.
"We don't know how long they'll have to stay up there. It depends on the situation with the dam," a local police official, who declined to be named, told Reuters.
The official death toll from the quake is 68,977 and is expected to rise, with 17,974 people still missing. Officials have said more than 30 landslide-blocked rivers could burst, flooding downstream towns and tent camps for refugees.
A major part of the construction effort to contain the rivers, a sluice designed to discharge water from a lake at Tangjiashan, has been completed, Xinhua quoted Yue Xi, deputy chief of the water and electricity section of the People's Armed Police Force, as saying.
He said the sluice was expected to drain water between Sunday and Tuesday.
Xinhua reported that contingency plans provided for the evacuation of up to 1.3 million people, depending on how the discharge of water proceeded.
Long convoys of trucks drove into the disaster area piled with tents and other supplies for evacuees. An Airbus 380 superjumbo, the world's largest passenger plane, flew into the regional city of Chengdu on Saturday with emergency supplies.
But Japan said it had shelved plans for its military to fly aid into the area because of China's historical sensitivities. It would have been the first deployment of the Japanese military to China since the end of World War Two.
The movement of thousands of refugees through the disaster area, some of them travelling not on official instructions but out of fear of aftershocks from the quake, continued to hinder the work of reuniting families.
Over 6,000 lost children have been reunited with their parents, but 1,800 have still not been able to make contact with family or relatives, Xinhua reported.
At Youxian, thousands of evacuees were living in a park on a hillside above the town, in tents erected between amusement park rides and statues of animals. They said they expected to return home after Tangjiashan was drained, but weren't sure when that might happen.
"The officials know what's happening, but we don't really know what's happening," said a middle-aged man named Yao Jizhen, who had been living in the park for three days.
A banner reading "unite together, no difficulty can break us" hung from a van nearby.
A health official at the park said there had been no outbreaks of illness there, but the Sichuan provincial health bureau has identified 205 cases of infectious disease contracted in the quake zone, including viral hepatitis, measles, and hand, foot and mouth disease, the official Beijing News reported.
Inside Youxian, remaining residents packed up to leave.
"Today is the last day. We have to go immediately. They've been a number of times to tell us," said Yang Zhonghai, a woman in her 50s who runs a small car wash, unpinning clothes from her washing line.
A few people, already uprooted once by the disaster, were defiant in the face of official orders for them to leave.
"For now we're not afraid. When the water starts to rise, we'll go," a middle-aged man surnamed Shen said outside his tarpaulin shelter by the Fu River.
Elsewhere in China, the death toll from torrential rain in 12 southern and eastern provinces, including Guizhou, Hunan and Hubei, rose to 93 people, with 43 missing.
The floods have affected over 9 million people and caused economic losses of 5 billion yuan ($A754 million), China News Service quoted local authorities as saying.