BEICHUAN, China —  China said the toll of dead and missing from last week's powerful earthquake jumped to more than 80,000, while the government appealed Thursday for millions of tents to shelter homeless survivors.

The confirmed number of dead rose nearly 10,000 from the day before to 51,151, Cabinet spokesman Guo Weimin told a news conference. Another 29,328 people remained missing and nearly 300,000 were hurt in the May 12 quake centered in Sichuan province, he said.

May 21: In this photo released by China's Xinhua news agency, a girl walks in the quake-hit Nanba Township of Pingwu County, Sichuan province

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The disaster left 5 million people homeless and leveled more than 80 percent of the buildings in some remote towns and villages near the epicenter. In bigger cities entire apartment blocks collapsed or are too dangerous to live in because of damage and worries about aftershocks.

"We need more than 3.3 million tents," Foreign Ministry spokesman Qin Gang told reporters, adding that 400,000 tents already have been delivered. It was the second call for tents from China in recent days.

"We hope and welcome international assistance in this regard. We hope the international community can give priority in providing tents," he said.

U.S. aid to earthquake victims totals $2.8 million, Ambassador Clark T. Randt Jr. said, including medical equipment and satellite images of damaged infrastructure. The American Red Cross had donated $10 million, and American companies operating in China have pledged more than $34 million.

Underscoring the need, Chinese President Hu Jintao visited two tent manufacturing companies in eastern Zhejiang province, urging workers to boost production to meet needs from the disaster area, state media reported.

Hu also chaired a meeting on the quake by China's highest governing body, the Standing Committee of the Political Bureau of the Communist Party, where leaders vowed to continue the rescue effort "to the last village," according to a statement.

Vital supplies must be ensured in affected areas and stability restored to society, the committee said, adding that schools should be reopened and agricultural production restarted.

In one quake-hit area, the rescue effort was called off and work turned to reconstruction. Rescue teams departed Dujiangyan, where workers were burying bodies and clearing rubble from collapsed buildings, The Beijing Times state-run newspaper reported.

In the effort to assure people the government was placing top priority on relief efforts, Premier Wen Jiabao returned Thursday to the disaster zone, the official Xinhua News Agency said — his second trip there following a visit immediately after the quake.

The government is also grappling with official estimates of more than 4,000 children orphaned by the quake, and received hundreds calls from people offering to adopt them.

Anger that so many children died because their school buildings were poorly built continued to simmer online and in state media. The Southern Metropolis News quoted a rescuer as saying that rubble from the Juyuan high school, where more than 270 students died, showed that no steel reinforcing bars were used in construction, only iron wire.

Pictures posted online of Wufu town, where some 200 students died when the Fuxin No. 2 Primary School collapsed, showed roads lined with wreaths. Piles of dusty school bags were among the rubble.

"The children did not die because of a natural disaster, they died because of a dangerous building," read a hand-painted banner strung across a roadway.

In Beichuan, the smell of bleach was overpowering as rescue workers in white safety suits sprayed disinfectant in the area. Villagers were picking up medicine from stands set up by the government.

The town's government offices opened Thursday at a hotel in neighboring Anxian county.

"Our previous office buildings collapsed, but our responsibilities, never," Ma Yun, head of the county's administrative office, was quoted as saying by Xinhua.

Blocked streams, earthquake-loosened soil, mudslides and the upcoming rainy season create the risk of secondary disasters that can make relief work and rebuilding even more difficult, officials with the Ministry of Land and Resources said Thursday.

Avoiding further geological disasters during relief work and rebuilding will be a "daunting task," said Yun Xiaosu, vice minister of land and resources.

The earthquake and aftershocks created 34 lakes, known as barrier lakes, as debris blocked rivers and streams throughout the earthquake area.

"The dangers at the barrier lakes are severe," Yun said. "The water level in some lakes is high and rising. If there's a break, it will cause severe damage."

People who might be in the way of breaks already have been evacuated, he added.

The region's rainy season starts in June, creating further problems and risk of major mudslides, Yun said.

The torch relay, a symbol of the country's hopes for the Beijing Olympics, restarted Thursday with a minute of silence at a container terminal in the eastern seaport city of Ningbo. The torch run has been toned down in the wake of the temblor.

Originally planned for next month, organizers said the Sichuan leg of the run would be delayed until just before the start of the Aug. 8 games.

In another sign of attempts to return to normal after the quake, officials in the Sichuan provincial capital of Chengdu ordered all government bodies and companies to resume regular operations, Xinhua reported.