China's weather bureau said it expects El Nino to cause heavy rainfall in the south and create droughtlike conditions in the north this year, but the intensity is likely to be moderate.

"The event will last until autumn, and be medium to strong, but it will not be as strong as during 1997-98, which was the strongest in history," the China Meteorological Administration said in a report on Friday.

El Nino, a warming of sea-surface temperatures in the Pacific basin, can disrupt weather across the world.

In 1997-98, it caused the worst flooding along China's Yangtze River in half a century, killing thousands as swollen rivers burst their banks and destroyed crops.

This year, the bureau forecasts serious summer flooding in the middle reaches of the Yangtze, the country's major rice and cotton production area, as well as areas along the Songhua River in the northeast, a major corn and rice area.

The majority of North China and parts of the northwest are most likely to be hit by summer drought, it said.

"North China may have higher-than-normal temperatures during summer, but the extreme hot weather will not last long or hit a large area," it said.

The El Nino that formed in May last year reduced the number of typhoons last summer and led to a warmer winter, said the report.