"Saving lives is still our top priority as long as hope of survival still exists," the official Xinhua news agency quoted Wen as saying.
President Hu Jintao headed to Sichuan early on Friday "to console the victims and inspect the rescue and relief work," the Xinhua news agency said. It will be his first trip to the region since the disaster struck.
Wen also repeated calls from the Communist Party leadership to ensure social stability as frustration and exhaustion grows among survivors, many of whom have lost everything and are living in makeshift tents or in the open air.
About 20,000 are confirmed dead from the quake and at least another 25,000 remain buried, officials said.
In the Sichuan town of Yingxiu, where bodies were lined up along the river bank, a Communist Party official warned that epidemics could break out if bodies were not soon buried or cremated.
"We are in urgent need of body bags," the official, Bai Licheng, told Xinhua. "Air-dropped food and drinking water are limited and far from meeting the demand," he added.
The Ministry of Health issued a notice ordering bodies to be cleaned where they were found and buried as soon as possible, far from water sources and downwind from populated areas.
More than 3,000 soldiers were racing the clock to search for survivors in Yingxiu, a township of about 6,600 people.
Bai said bodies were still trapped in the debris and blocked roads meant that heavy lifting gear could not get through.
China has mobilized 130,000 army and paramilitary troops to the disaster area, but the quake buckled roads and triggered mountain landslides, meaning that relief supplies and rescuers have struggled to reach the worst-hit areas.
Struggling To Cope
In the town of Shifang, a small hospital struggled to cope with injured patients, who were being treated in any space available -- including a under a covered car park at the back of the building and under tents on the pavement.
Doctors and nurses rushed around, checking dressings, changing saline drips and administering to the wounded.
"We've seen nobody come here from the government," said one woman, tending to her injured son. "They're trying to help, but they've been so busy," added a young man standing next to her. "In Mianzhu alone there's thousands dead," he said, referring to a nearby area.
Hundreds of damaged dams have also raised fears of collapse or flooding that could inundate towns and cities that are already struggling to recover from the quake.
China has asked the United States for satellite images to help locate victims and identify damaged infrastructure. In Sichuan and neighboring Chongqing, at least 17 reservoirs have been damaged, some dams have cracked or are leaking water, and officials have warned the full extent of the hazard was as yet unclear.
China was also accepting foreign help to bolster rescue efforts in the disaster, the deadliest since more than 240,000 people were killed in a 1976 earthquake in the northeastern Chinese city of Tangshan.
The first foreign rescue team, a group from about 60 people from Japan, also reached Sichuan on Friday. China has accepted further offers of rescue teams from Russia, South Korea and Singapore, the Foreign Ministry said.
In the epicenter, Wenchuan, Chinese air forces succeeded for the first time on Thursday in dropping equipment, Xinhua said, citing military sources. Such airdrops had earlier been stymied by heavy rain and cloud cover.