Xinhua, Chen Kai/AP The city of Yingxiu was badly stricken by the largest earthquake China has experienced in three decades. Thousands in the region remain buried in the wreckage.

LUOSHUI TOWN, China — Troops dug burial pits in this quake-shattered town and black smoke poured from crematorium chimneys elsewhere in central China as priorities began shifting Thursday from the hunt for survivors to dealing with the dead. Officials said the final toll could more than double to 50,000.

As the massive military-led recovery operation inched farther into regions cut off by Monday's quake, the government sought to enlist the public's help with an appeal for everything from hammers to cranes and, in a turnabout, began accepting foreign aid missions, the first from regional rival Japan.

Millions of survivors left homeless or too terrified to go indoors faced their fourth night under tarpaulins, tents or nothing at all as workers patched roads and cleared debris to reach more outlying towns in the disaster zone.

Health officials said there have been no outbreaks of disease so far, with workers rushing to inoculate survivors against disease, supply them with drinking water, and find ways to dispose of an overwhelming number of corpses.

"There are still bodies in the hills, and pits are being dug to bury them," said Zhao Xiaoli, a nurse in the ruined town of Hanwang. "There's no way to bring them down. It's too dangerous."

Sites for burials prepared

Troops in the town of Luoshui in a quake-ravaged area used a mechanical shovel to dig a pit on a hilltop. Two bodies wrapped in white sheets lay beside it. Down the hill sat four mounds of lime.

In a sign of nervousness, 50 troops lined the road outside Luoshui. Five farmers watched them dig a burial pit, after performing brief funerary rites.

Across the quake zone in Dujiangyan, troops collected corpses and loaded them onto a flatbed truck. Thick black smoke streamed from the twin chimneys of the town's crematorium.

Fears about damage to a major dam in the quake zone appeared to ease. The Zipingpu dam had reportedly suffered cracks from the disaster, but there was no repair work or extra security at the dam when it was reached Thursday by an AP photographer, indicating the threat to the structure had likely passed.

Just behind the dam, soldiers set up a staging area preparing speed boats to lower into the reservoir and ferry soldiers in lifejackets, engineers and medical staff up river to Yingxiu, a town flattened by the quake.

The emergency headquarters of the State Council, China's Cabinet, said the confirmed death toll had reached 19,509 — up more than 4,500 from the day before. The council said deaths could rise to 50,000, state media reported.

The provincial government said more than 12,300 remained buried and another 102,100 were injured in Sichuan, where the quake was centered.

More people unearthed

Experts said hope was quickly fading for anyone still caught in the wreckage of the magnitude-7.9 quake, the most powerful in three decades in quake-prone China.

In Dujiangyan, a 22-year-old woman was pulled to safety after more than three days trapped under debris. Covered in dust and peering out through a small opening, she waved and was interviewed by state television as hard-hatted rescuers worked to free her.

"I was confident that you were coming to rescue me. I'm alive. I'm so happy," the unnamed woman said on CCTV.

Premier Wen Jiabao, who has been in the quake zone since Monday as the public face of a usually remote communist leadership, urged those helping the injured to keep up their efforts. Repeating a phrase that has become a government mantra this week, Vice Health Minister Gao Qiang said every effort would be made to find survivors.

"We will never give up hope," Gao told reporters in Beijing. "For every thread of hope, our efforts will increase a hundredfold. We will never give up."

Cleanup efforts continue

With more than 130,000 soldiers and police mobilized in the relief effort, roads were cleared Thursday to two key areas that took the brunt of the quake, with workers making it to Wenchuan at the epicenter and also through to Beichuan county, the Xinhua News Agency reported.

Power was restored to most of Sichuan for the first time since the quake, although Beichuan county remained without electricity, Xinhua said.

In Dujiangyan, on the road between the provincial capital of Chengdu and the epicenter, a dozen bodies lay on a sidewalk as police and militia pulverized rubble with cranes and back hoes. The bodies were later lifted onto a flatbed truck, joining some half-dozen corpses.

Fireworks were set off every few minutes and families burned incense, candles and spirit money. Such traditions meant to send the dead peacefully into the afterlife were once banned by the communist authorities but have revived in recent years with free-market reforms and rising prosperity.

More donations needed

In an appeal posted on its Web site, the Ministry of Information Industry called on the Chinese to donate rescue equipment including hammers, shovels, demolition tools and rubber boats — 100 cranes were also needed, it said.

The International Federation of Red Cross and Red Crescent Societies has also issued an emergency appeal for medical help, food, water and tents.

After initially refusing offers of foreign aid workers, China welcomed a Japanese rescue team.

Japan and China have been at odds for years over disputed borders, Japan's treatment of its wartime invasion of China, anti-Japanese protests in China and general Japanese unease over Beijing's rapidly growing diplomatic, military and economic power.

China had so far received international aid worth more than $100 million and materials worth more than $10 million, Foreign Ministry spokesman Qin Gang said at a briefing. But it still needed supplies of tents, clothes, communication equipment and medicines, he said.