Rescuers struggled to reach a remote, rural corner of southwestern China on Sunday as the toll of the dead and missing from the country's worst earthquake in three years climbed to 203 with almost 1,000 serious injuries.

The 6.6 magnitude quake struck in Lushan county, near the city of Ya'an in the southwestern province of Sichuan, close to where a devastating 7.9 quake hit in May 2008, killing 70,000.

Most of the deaths were concentrated in Lushan, a short drive up the valley from Ya'an, but rescuers' progress was hampered by the narrowness of the road and landslides, as well as government controls restricting access to avoid traffic jams.

"The Lushan county centre is getting back to normal, but the need is still considerable in terms of shelter and materials," said Kevin Xia of the International Federation of Red Cross and Red Crescent Societies.

"Supplies have had difficulty getting into the region because of the traffic jams. Most of our supplies are still on the way," Xia said.

In Ya'an, relief workers from across China expressed frustration with gaining access to Lushan and the villages beyond, up in the mountains.

"We're in a hurry. There are people that need help and we have supplies in the back (of the car)," said one man from the Shandong Province Earthquake Emergency Response Team, who declined to give his name.

The Foreign Ministry thanked foreign governments for offers of help, but said the country was able to cope.

"At present, Chinese rescue and medical capabilities are guaranteed and relief resources are sufficient," it said.

In Lushan, doctors and nurses tended to people in the open or under tents in the grounds of the main hospital, surrounded by shattered glass, plaster and concrete. Water and electricity in the area were cut off by the quake, but the spring weather is warm.

"I was scared. I've never seen an earthquake this big before," said farmer Chen Tianxiong, 37, lying on a stretcher between tents, his family looking on.

Nearby, an elderly woman sat dazed mumbling to her son, while nurses wiped blood from another woman's foot as her husband cradled her head.

In another tent, Zhou Lin sat tending to his wife and three-day-old son who were evacuated from a Lushan hospital soon after the quake struck on Saturday.

"I was worried the child or his mother would be hurt. The buildings were all shaking. I was extremely scared. But now I don't feel afraid any more," said Zhou, looking at his child as he slept soundly wrapped in a blanket on a makeshift bed.

Premier Li Keqiang flew into the disaster zone by helicopter to comfort the injured and displaced, chatting to rescuers and clambering over rubble.

"Don't be sad, we will rebuild after this disaster and your new homes will be even better than before," state media quoted him as telling residents.

The Ministry of Civil Affairs put the number of dead at 179 and missing at 24, with almost 11,500 injured, 960 of them seriously.

Chen Yong, the vice director of the Ya'an city government earthquake response office, told reporters that the death toll was unlikely to rise dramatically.

"We understand the situation in most areas. Most of the casualties have been reported. In some remote mountain areas, it is possible that we don't fully understand the situation," he said.

SCHOOLS WITHSTAND QUAKE

But no schools had collapsed, unlike in 2008 when many poorly constructed schools crumpled causing huge public anger, prompting a nationwide campaign of re-building.

"Our schools are the safest and sturdiest buildings," Chen said. "The Chinese government has put a lot of money into building schools and hospitals. I can guarantee that no schools collapsed."

Xinhua news agency said 18,000 troops were in the area to help with rescue efforts.

Rescuers in Lushan had pulled 91 survivors out of rubble, Xinhua said. In villages closest to the epicenter, almost all low-rise buildings had collapsed, footage on state television showed.

The China Meteorological Association warned of the possibility of landslides in Lushan county, with more than 1,400 aftershocks registered.

Ya'an is a city of 1.5 million people and is considered one of the birthplaces of Chinese tea culture. It is also the home to one of China's main centers for protecting the giant panda.

Sichuan is one of the four major natural gas-producing provinces in China, and its output accounts for about 14 percent of the nation's total.

Sinopec Group, Asia's largest oil refiner, said its huge Puguang gas field was unaffected.

The U.S. Geological Survey initially put the magnitude at 7, but later revised it down.

In 2010, a 7.1 magnitude earthquake killed 2,700 people in Yushu, a largely Tibetan region in northwest China.