China's exhausted flood fighters remained on guard Tuesday as a new surge of high water barreled down the Yangtze River, threatening to overwhelm dikes weakened by a summer of devastating floods.

China's flood control headquarters described the situation as "extremely serious." It warned that along a 180-mile stretch of the river, water levels stood at historic highs and some places have been inundated for 60 days or more.The new Yangtze flood crest - the seventh so far in a summer of flooding that has killed thousands of people and left millions homeless - was expected to plunge through the Three Gorges Dam area and enter the middle Yangtze Tuesday.

Zhou Wenzhi, vice minister of water resources, said the crest was expected to reach the city of Shashi by Tuesday night.

But water levels on the river at Shashi were expected to remain below 1481/2 feet - the level at which officials have said they might dynamite dikes to deliberately flood an area where half a million people live to save cities downstream.

This summer has seen the worst flooding in 44 years along the Yangtze in central China, and the worst in decades in northeastern China, affecting a total of 250 million people.

Government spokesman Zhao Qizheng raised the official flooding death toll Tuesday from "more than 2,000" to "not expected to surpass 4,000."

Given China's population of 1.2 billion and the sheer scale of the flooding, "the figure of casualties was very, very small," Zhou said at a news conference.

He discounted reports that thousands of people had been killed in flooding in hard-hit central Hubei Province, saying instead that 44 people were killed.

However, he added that most efforts were being expended in fighting the floods, so the assessments of deaths and damages were lagging.

Zhou predicted that high flood levels on the middle and lower reaches of the Yangtze River would persist for another 20 days - as long as no more heavy rains fall. With good weather, China's flood season should be over by October, he said.

President Jiang Zemin noted the heroic efforts of 2.1 million civilians and soldiers manning dikes on the Yangtze. But he predicted that the devastation will not significantly impact China's economy.

In an interview with current and former members of the Board of Directors of The Associated Press, Jiang also lamented nature's ability to overwhelm modern technology.

"We can predict the rainfall, but can't stop it from falling from the skies," Jiang said.

Vital dikes that protect major industrial centers and rich farmland are "once again facing a serious test," the flood control headquarters said.

While the flood crest was not expected to reach the highs of those that preceded it, flood fighters were told to prepare.

"Persevere and persevere again to win the climatic battle in the fight against floods," the Communist Party newspaper People's Daily exhorted.