Tens of thousands of survivors of China's earthquake were mired in misery on Sunday amid pouring rain and a lack of adequate shelter, food and medicine, state media reported.

The appalling conditions described by Sichuan News Online in the quake-stricken town of Maoxian underlined the huge humanitarian challenges faced by China nearly a week after its worst earthquake in a generation.

About 50,000 people including soldiers and rescue workers had spent the night under leaky makeshift rain shelters, awakening to a miserable wet and windy dawn on Sunday in the shattered town, it said.

"Due to the rain in Maoxian, the people have gone from one disaster to another," its reporter in the area wrote.

"Ninety percent of the shelters are leaking. The people jostle to claim the few areas not leaking rain."

The report said people there included residents who had presumably lost their homes in last Monday's 7.9-magnitude quake, as well as a number of tourists.

Maoxian is one of the towns closest to the epicentre of the quake, which China estimates has killed 50,000 people. Massive damage to infrastructure also has cut off large areas in the affected region, hampering the relief effort.

The quake victims were still shivering in misery Sunday amid the wail of crying children, it said.

"Crying, the people said, 'We want our families! We want to go home!'" the report said, adding that shelter, food, medicine and water were badly needed.

Only about 20,000 tents had been brought to the area, it said.

Authorities are racing to prevent the outbreak of disease in quake-hit areas.

The World Health Organisation warned on Saturday the lack of safe drinking water or proper waste disposal along with cramped conditions in temporary shelters was "conducive" to outbreaks.