A lake created by the Chinese earthquake which threatens to unleash a devastating flood is still rising despite urgent efforts to drain the waters off safely, Xinhua news agency reported today.
Troops fired missiles and used dynamite to help blast out a sluice channel to drain off a huge volume of water which has built up behind the mud-and-rock dam at Tangjiashan.
Landslides blocked the Tongkou River in last month's 7.9 magnitude quake, creating the biggest of more than 30 "quake lakes" formed by a disaster which has already killed 69,000 people.
Worried that it could burst in a sudden rush, officials have evacuated more than 250,000 people from downstream areas.
A strong aftershock hit the region on Sunday evening, shaking the dam for about 20 seconds and causing what a Xinhua reporter described as massive landslides in surrounding mountains.
There have been thousands of aftershocks since the May 12th quake. The US Geological Survey measured Sunday's at magnitude 5.0, and Chinese officials said they were monitoring its impact on the Tangjiashan dam.
Some 600 armed police and soldiers have worked for six days to dig a 475-metre channel to run off water from the lake in Beichuan County.
The lake's water level was 741.82 meters above sea level at midday today, 1.45 meters higher than the sluice, state-run Xinhua said.
Military engineers have fired missiles to blast boulders in the channel to accelerate drainage, and soldiers have finished building one third of a second channel, said Liu Yongjian, a People's Liberation Army (PLA) officer in charge of the operation.
"We have also prepared underwater blasts to deepen the channels for accelerated drainage," said Mr Liu.