Weeks of high waters cracked soggy dikes protecting cities along the Yangtze River Saturday, threatening more flooding in an area already inundated.

The state disaster relief agency said high waters surged anew on the upper Yangtze River, which could add to the flooding problem downstream. Governor Wang Maolin said dikes in central Hunan province already were soggy and seriously damaged.While the latest Yangtze flood receded Saturday around Hunan's Dongting Lake, its retreat exposed fractures in protective embankments. About 830,000 soldiers and civilians worked around the city of Yueyang to shore up dikes and patch cracks, one 230 feet long, state media reported.

The Yangtze River basin has taken the brunt of China's worst flood season in 44 years. At least 2,000 people have died nationwide and millions more have been left homeless. The government, often reluctant to divulge bad news, has not revised those tallies in two weeks.

Since then, floodwaters have smothered villages and threatened some of the most important industrial centers in the northeast.

Soldiers rushed to close a breach that opened in the third and last line of levees keeping the Nen River out of the Daqing oil field and city, state radio reported.

Since overwhelming the dike Thursday night, the Nen has washed away a highway and inundated nearly half the area's farmland, the Liberation Daily reported.

Xinhua said oil production continued, despite the inundation of 1,443 oil wells and the shutdown of 282 wells.

In Harbin, Heilongjiang's capital 100 miles to the southeast, the Songhua River swelled to higher record levels and began undermining the 15-mile levee by the city's industrial center.

Foundations under a riverside pumping station and apartment complex gave way overnight and residents were evacuated, state television reported. Video footage showed a crack running down the two-story pumping station, part of which sank a foot into the saturated ground.

Trucks brought more soldiers into Harbin on Saturday to reinforce the levee.

"As long as the dikes are all right, we are all right and our homes are safe," read one banner in the city.

With local clinics and hospitals in many parts of the country under water, health officials faced a shortage of medicines and equipment.