BEIJING - Water levels have risen to critical levels along vast Chinese rivers and floods have spread to the north while a tornado hammered 33 villages in the east, Chinese media said on Thursday.

More than 500 people have been killed since the summer floods started, but despite the huge human and economic damage, the disaster has failed to gain world attention in the same way as floods in England, in which three deaths have been reported.

Four deaths were reported in the normally arid northwestern province of Gansu and the neighbouring frontier region of Xinjiang, Xinhua news agency said.

Two farmers in Xinjiang's Huocheng county were swept away by flood water triggered by heavy rain that started on Tuesday, Xinhua said.

"At least 48 herdsmen and 13,000 goats have been stranded for nearly two days in a mountainous area in northwestern Xinjiang after a landslide cut off their path," it said.

On Wednesday, a tornado raged through 33 villages in Yinshang county in the dirt-poor eastern province of Anhui.

The villages were among the worst-hit in weeks of serious flooding along the swollen Huai River which had displaced hundreds of thousands of residents, Xinhua said.

"It is like adding frost to the snow," it said.

There have been no reports of casualties from the tornado, but water levels along the Huai remained at alarming levels.

In the southwestern province of Guizhou, at least one person died and 645,000 people were affected by rainstorms this week, Xinhua said.

Water levels of two rivers in the scenic Xiangxi area in the central province of Hunan rose to up to seven metres above the danger levels after days of downpours, prompting dams to open flood gates, the official news agency said.

Some 26,000 people in central Hubei have been mobilised to check embankments as flood peaks on the Yangtze River, China's longest, and its main tributary Han River approached provincial capital Wuhan, Xinhua said.