Correspondents says that hopes of finding survivors fade with each passing day.
But Vice Health Minister Gao Qiang said: "We will make out utmost effort when there is only a glimmer of hope and we will never give up."
He said there would be an increasing demand for medicines and sophisticated medical equipment as the rescue operations continue and survivors were treated for injuries such as bone fractures, crushed internal organs and kidney failure.
Thousands of people have been rescued from affected areas.
But some stories in the hardest-hit areas give rescuers more hope.
In Beichuan County - one of the hardest hit areas where about 5,000 people died - a three-year-old girl was rescued alive. She had been buried under the debris since the quake, with the bodies of her parents shielding her.
Troops were deployed to Zipingku dam, to repair cracks caused by the earth tremors. It has now been pronounced stable and safe, but there are concerns for almost 400 other dams in the area that may also have been damaged, he says.
The Chinese military plans to conduct large-scale airdrops of food, clothing and blankets over the worst-hit areas, including the districts of Beichuan and Wenchuan.
Chinese soldiers tackle 'extremely dangerous' cracks in Zipingku Dam
The helicopters are needed because many of the roads in the mountainous area near the epicentre have been badly damaged by the earthquake or have been covered by landslides.
Prime Minister Wen Jiabao said: "We must use all our forces, and save lives at whatever costs.
"Life is the most precious thing."
The relief effort has also been hampered by bad weather, while an aftershock was reported in Yingxiu, a town close to the quake's epicentre where more than three-quarters of the 10,000 residents perished.
A local resident who had walked out of one of the isolated villages, Qingping, said half of the village's population of 2,000 was injured, and survivors were in need of medicine and drinking water, Xinhua reported.
The head of a police unit sent into the disaster zone said the losses had been severe.
"Some towns basically have no houses left," Wang Yi told Sichuan Online news site. "They have all been razed to the ground."
The official toll for the number of dead now stands at 14,866, Xinhua news agency reports.
RECENT CHINA QUAKES
March, 2008: 7.2 quake in Xinjiang - damage limited
February 2003: 6.8 quake in Xinjiang - at least 94 dead, 200 hurt
January 1998: 6.2 quake in rural Hebei - at least 47 dead, 2,000 hurt
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