May 31 (Bloomberg) -- China began removing workers clearing an earthquake-formed lake that's threatening to collapse and flood nearby areas, where 1.3 million people were told yesterday to prepare to flee.

Fifteen relief workers, mostly members of the People's Armed Police Force, were lifted from the Tangjiashan lake embankments by helicopter this morning as waters continue to swell, state-run news agency Xinhua reported.

About 350 police and others are expected to leave today, and the rest by noon tomorrow, according to Xinhua. Tangjiashan is the biggest of more than 30 lakes created after landslides caused by the May 12 earthquake blocked rivers. It holds more than 173 million cubic meters of water, according to the Ministry of Water Resources -- a volume equivalent to 1 billion barrels of oil, or enough to meet China's energy needs for 138 days.

``It's going to be a critical few days,'' Francis Markus, spokesman for the International Federation of Red Cross and Red Crescent Societies, said in a telephone interview from quake- stricken Sichuan. `` If more large evacuations are required, this will further strain what's already a very difficult humanitarian situation.''

Markus said the Red Cross is appealing for more international assistance to provide water, sanitation and shelter.

Chinese President Hu Jintao arrived in Shaanxi province this morning to direct earthquake relief efforts there, as blocked rivers threaten to flood survivors of the country's deadliest earthquake in 32 years. About a quarter of the residents in Shaanxi's Lueyang County evacuated as of last night amid concerns of potential aftershocks and flooding, Xinhua said.

`Extremely Dangerous'

The Tangjiashan lake is in an ``extremely dangerous'' state, the ministry said yesterday on its Web site. More than 700 soldiers and officials are using 46 earthmoving vehicles to dig channels and drain the swelling waters. About 200,000 people left an area downstream where workers are diverting the runoff.

More than 5.2 million people live in and around Mianyang, the nearest city to the Tangjiashan lake. China is preparing to evacuate as many as 1.3 million in case the lake's embankments collapse and unleash a flood, officials said yesterday.

Over 90,000 Chinese soldiers are now in the earthquake- stricken regions to help with relief operations, Xinhua said.

Gansu, the north-central Chinese province affected by the quake, plans to complete reconstruction, including of highways and reservoirs, by 2010, Xinhua cited Governor Xu Housheng as saying.

School Safety

Meanwhile, China ordered the immediate evacuation of any schools failing to meet safety standards, according to a statement on the central government's Web site. China has said it will investigate why many schools collapsed in the earthquake as the number of students killed has become a focus of public grief and of anger at local officials.

Former French Prime Minister Jean-Pierre Raffarin offered his condolences to earthquake victims at the Chinese embassy yesterday. President Nicolas Sarkozy sent three special envoys to China in April, including Raffarin, after France drew the nation's ire for the jostling of a wheelchair-bound Chinese athlete by a protester in Paris that month.

The death toll from the quake rose to 68,977, Xinhua reported today. More than 15 million people have been displaced.

The earthquake was the most powerful to hit China since a magnitude 8.6 quake struck Tibet in 1950, killing 1,526 people.

A 7.5 magnitude temblor in Tangshan in the northeast killed 250,000 people in 1976, according to the USGS. China's seismology department said the Sichuan quake had a magnitude of 8.

To contact the reporters on this story: Josephine Lau in Beijing at jlau22@bloomberg.net

Last Updated: May 31, 2008 04:36 EDT