Rains, floods wreak havoc in China

(Adds threat of dikes being breached)

BEIJING, July 21 (Reuters) - The death toll from storms in east China's coastal Shandong province has risen to 40, the official Xinhua news agency said on Saturday, citing the provincial civil affairs bureau.

China's flood season, which usually lasts from May to September, has already killed hundreds of people this year and caused a plague of rats fleeing rising waters in the southeastern province of Hunan.

Xinhua cited officials with the flood control centre in eastern Anhui province as saying that they faced a "severe" challenge in controlling flooding in the middle and lower reaches of the Huai River in the coming days.

Dikes in those areas, already soaked for more than two weeks, would be at a heightened risk of giving way in the coming 10 days as water levels are expected to remain dangerously high for at least that long, the agency said.

Heavy rain is forecast to continue to hit large swathes of China over the weekend, including the central Huai River basin.

Hundreds of thousands of residents along the Huai, which runs through the central province of Henan as well as Anhui and Jiangsu in the east, have had to evacuate their homes.

Rising water levels there forced another 67,000 people from their homes in Anhui on Thursday, Xinhua said.