Beijing - Fog on Tuesday impeded the search for a helicopter that crashed while on an aid mission in the earthquake zone of south-western China.

About 10,000 soldiers were taking part in the three-day search for the remnants of the Russian Mi-171, the China Daily reported. It crashed Saturday with 19 people on board in a mountainous area near the city of Yingxiu during thick fog and turbulence.

Meanwhile, the release of water has been delayed at a lake in Tangjiashan that was created by earthquake debris and threatens to overflow, the official Xinhua news agency said.

Soldiers finished a diversionary canal that is to be used to siphon off the water from the lake in the next several days, but a lack of rain has slowed the rise of its water, prompting experts to estimate the draining of the reservoir would not begin before Thursday, Xinhua said.

More than three weeks after the May 12, magnitude-8 earthquake, the death toll rose Tuesday to 69,107 while the number of missing was put at 18,230. (dpa)