Premier Wen Jiabao landed on the dam of Tangjiashan quake lake in Sichuan province Thursday as water flowed into a sluice built a few days ago.
The premier walked out of a helicopter after it landed on the landslide-created dam on the Jianjiang River near Beichuan in Sichuan province to review the situation first hand.
The presence of the premier on the dam allayed fears somewhat that the quake lake was about to break its bank.
CCTV footage showed Wen standing on the bank of the diversion channel, from where water was flowing, and talking with soldiers and officials.
"This is a critical moment for the Tangjiashan quake lake, and the most important thing is to ensure there are no casualties," Wen was quoted by Xinhua as saying. The premier was on his third trip to the quake-hit zone.
Rescue workers let the lake water flow into the sluice to prevent the dam from bursting its bank and flooding human habitation downstream.
A spokesman for the local disaster relief headquarters had warned late on Wednesday that the quake lake could break its banks because of the aftershocks, and rain in the upper reaches of the river.
"Water has been seeping from the dam," he said.
The water level in the largest quake lake, which holds more than 200 million cu m of water, rose to 739 m yester day, just 1.2 m below the overflowing point.
Landslides triggered by the May 12 quake have formed 34 such lakes, and People's Liberation Army (PLA) soldiers had to blast a dam in Qingchuan county on Wednesday to drain out water from one.
More than 250,000 people have been evacuated from Beichuan county and Mianyang city.
Troops carried out a thorough check in Jiangyou's towns Thursday to ensure that no villager had returned, Xinhua said.
The death toll in the quake increased by five to 69,127 by noon Thursday, and 373,612 people were injured and 17,918 missing, the State Council Information Office said.
Hospitals have treated 97,631 injured, 74,165 of who have been discharged.
Relief supplies continued to pour into the quake zone. By noon Thursday, 820,000 tents, 4.71 million quilts, 11.86 million garments, 731,700 tons of fuel oil and 1.54 million tons of coal had been delivered.
Domestic and foreign donations had reached 43.764 billion yuan ($6.33 billion) by noon Thursday, and 12.795 billion yuan had been forwarded to the earthquake-affected areas.
The National Audit Office (NAO) said Thursday that auditors are checking the use of goods and funds in earthquake relief, and the results will be released to the public around June 20.
China has dispatched more than 6,000 professionals from the NAO and local audit authorities for on-site supervision of relief resources.
In the 24 hours till Thursday noon, 166 aftershocks were recorded, the China Earthquake Administration said, and three of them were between 4 and 5 magnitude.
An aftershock of magnitude 5 jolted Qingchuan county at 12:41 pm Thursday, the administration said. But there were no immediate reports of damage or injuries.
Till date, 10,419 aftershocks have been recorded, and they have raised the fear of the Tangjiashan quake lake breaking its banks and flooding human settlements downstream.