China struggled to keep roads open to provide a lifeline for quake survivors, while the government warned Wednesday that rebuilding after the disaster would be "arduous."
The magnitude 7.9 quake that struck May 12 sent dirt and rocks tumbling into valleys, blocking roads to hinder relief efforts and clogging rivers that have developed into fast-rising lakes.
"We are racing against time to repair damaged infrastructure," said Mu Hong, a deputy director at the National Development and Reform Commission, the country's top economic planning body, adding that some roads were only reopened on a temporary basis.
"The high risk of mudslides and landslides makes our efforts more difficult," he said.
Rebuilding infrastructure is just a part of the recovery effort that government officials have said earlier would take three years in hard-hit Sichuan province.
"Due to the immense magnitude of loss that resulted from the quake, production recovery and reconstruction of the quake-hit region will be arduous in the near future," the commission said in a statement.
In the disaster zone, 158,000 people have been evacuated and dozens of villages emptied in case the newly formed Tangjiashan lake bursts before soldiers and engineers can drain it, the official China Daily said Wednesday.
Troops used explosives to clear debris and helicopters to airlift heavy moving equipment to dig drainage channels from the lake, located about 2 miles above the devastated town of Beichuan.
Premier Wen Jiabao told a meeting of the State Council, China's Cabinet, that handling the danger from the swelling lakes was the "most pressing task" in the disaster recovery effort, the newspaper said.
The government has allocated $28.6 million to deal with the swelling lakes, the official Xinhua News Agency said. Of 34 lakes created by the earthquake in the mountainous province, 28 were at risk of bursting, according to the agency.
Also on Wednesday, Japanese defense and foreign ministry officials said they were considering a request from China to send troops to help in quake relief efforts. It would be the first significant Japanese military dispatch to China since World War II, when Japan conquered large swaths of China before being defeated by the Allies.
Meanwhile, the number of confirmed deaths from the quake climbed toward an expected toll of more than 80,000. China's Cabinet said Wednesday that 68,109 people were killed, with 19,851 still missing.
State media reported that torrential rain in southern and eastern China has killed at least 50 people in the past week and left 4,000 stranded.
The poor and remote southwestern province of Guizhou has been hardest hit, with 36 dead and another 14 missing, the official Xinhua news agency said.
"Tents, quilts and clothes have been sent to Wangmo County in Guizhou, which has been severely hit by rain and floods," it added.
Hunan, Hubei and Guangxi provinces have also been affected, and hundreds of buildings have been buried by landslides and roads cut-off, Xinhua said.
The China Meteorological Administration warned that more rain is expected in eastern and southern China over the next three days, it added.
"The State Flood Control and Drought Relief Headquarters issued a warning urging provinces to keep a close watch on the changing weather and act to avert possible danger," Xinhua said.
Officials have warned that heavy summer rains could place further pressure on dams, which if breached, would endanger tens of thousands of people in downstream villages.