Chinese troops racing to drain a lake formed by the recent earthquake have made substantial progress digging a diversion channel.
The landslide-blocked river at Tangjiashan in southwest China's Sichuan province is now the most pressing danger after an earthquake devastated the region on May 12th.
Hundreds of troops have removed more than one third of the earth for a channel intended to ease pressure from the rising waters, an official spokesman said on Friday. They have also created emergency escape paths in case a mud and rock dam gives way.
Up to 190,000 residents downstream had moved to higher ground to avoid a surge of water if the blockage suddenly gives way.
The official Xinhua news agency said the water level was nearly 23 metres (75 feet) below the lowest point of the barrier, which experts have said could give way quickly once breached.
The death toll from the quake is over 68,500 and is sure to rise, with 20,000 still reported missing. Aftershocks have toppled 420,000 houses, most already uninhabitable.
The reconstruction work has only just begun, and thousands of survivors are now threatened by the "quake lakes", formed by landslides, that could break through the natural dams, flooding downstream
A massive relief effort to provide food, tents and clothing for millions and rebuild houses and infrastructure, including many destroyed schools, is expected to take up to three years.
Japan has shelved plans for its military to fly tents and blankets to China, however, due to concerns in China over the move, a senior government official said today.
Relations between the two countries have long been troubled by their wartime past.