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.

The disaster left 5 million people homeless and leveled more than 80 percent of the buildings in some remote towns and villages areas near the epicenter. In bigger cities whole apartment blocks collapsed or are now 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 have already 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.

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 the official Xinhua News Agency.

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.