A government official has warned of more flooding in late July and early August along the Yangtze River and in North China as torrential rains are expected to hit the country in the next few weeks.

Liu Zhiyu, chief of the Hydrology Intelligence and Forecasting Center of the Ministry of Water Resources, said 80 percent of the country's major floods take place between late July and early August when the rainstorms are usually stronger and cause larger floods.

"That is why there are still tough tests ahead, and the situation could be even more complicated and changeable when coupled with the effects of El Nino," he told a news briefing on Thursday.

More than 1,500 counties across 28 provinces have reported floods, with 237 fatalities and 93 people missing as of Wednesday, said Zhang Jiatuan, spokesman for the Office of State Flood Control and Drought Relief Headquarters.

Some 147,200 houses have been destroyed, Zhang said, adding that direct economic losses were 147 billion yuan ($22 billion).

The National Meteorological Center issued a blue alert on Thursday evening as torrential rain is expected to batter areas in East and Central China between 8 pm Thursday and 8 pm Friday.

China has a four-tier warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.

Some areas in Hubei, Anhui and Jiangsu provinces are expected to be hit by rainstorms that will bring total precipitation of 100 to 150 millimeters.

Flood control authorities cannot afford any sloppiness "as the water level in the middle and lower reaches of the Yangtze River is still above the alert level", Zhang said.

The water level of Taihu Lake, which hit a record high last week, is now slowly receding, he said.

He said the risk of flooding is mainly in the small and medium-sized rivers, as the flood control capacity of large rivers has been remarkably improved since 1998, when floods battered much of the country and killed more than 3,000 people.

Flooding from streams and medium-sized rivers account for 70 to 80 percent of flood-related casualties nationwide, according to the headquarters.

Zhang said the low flood prevention capacity of small rivers has been exposed in recent years as the central government and local authorities have mostly focused on the flood prevention in large rivers.

"The small and medium-sized rivers are in dire need of more investment in flood prevention," he said.

[email protected]

Armed police officers check a landslide site at a section of highway inMarkamcounty in the Tibet autonomous region on Thursday. The landslide was the result of rain. Tan Zeyang / Xinhua