(Corrects day in paragraph 1, official Xinhua correction on size of lake, paragraph 3)
BEIJING, Aug 5 (Reuters) - An earthquake in China on the weekend triggered landslides that have blocked rivers and created rapidly growing bodies of water that could unleash more destruction on survivors of the disaster that killed 410 people, state media reported on Tuesday.
More than 2,300 people were injured and 12 are missing after the magnitude 6.3 earthquake struck the southwestern province of Yunnan on Saturday. It was the region's strongest quake in 14 years and destroyed thousands of buildings.
The earthquake has formed a huge barrier lake containing more than 49.6 million cubic metres (1,750 million cubic feet) of water, and 4,200 residents threatened by it had been evacuated, Xinhua reported, quoting an expert in charge.
"Its water level is increasing at a speed of 30 cm per hour, putting seven power stations in the lower reaches in danger," the news agency said.
Thousands of police, soldiers and fire fighters have been sent to help but rescue work is being hampered by poor infrastructure, aftershocks and debris in the mountainous region.
On Monday, an army doctor went missing while trying to swim across another lake to help a villager search for his missing wife, Xinhua said.
Workers have begun letting water out of two reservoirs which were cracked by the quake, it said.
Premier Li Keqiang went to the disaster zone on Monday and media broadcasts and websites have been carrying pictures and footage of him trudging through devastated areas and offering condolences to survivors.
The seriously injured would be taken for treatment outside the quake zone, while the government would take quarantine measures to prevent epidemics, Li said, according to Xinhua.
Official media have also reported acts of heroism including a soldier distributing food fainting from hunger and university students forsaking their studies to join the rescue effort.
Yunnan's provincial government pledged 23 million yuan ($3.73 million) for disaster relief, while the Red Cross Society of China donated 33.36 million yuan ($5.41 million), Xinhua said.
Earthquakes frequently strike the region. A quake in Sichuan province, also in the southwest, in 2008 killed almost 70,000 people. (Reporting by Fiona Li, Megha Rajagopalan and Paul Carsten; Editing by Robert Birsel)