Passengers were trapped in chest-high water inside a Chinese underground train as a flash flood swamped the subway.

Heavy rain pounded the central Chinese province of Henan on Tuesday, bursting the banks of major rivers, flooding the streets of a dozen cities.

No deaths or casualties have been reported, but the daily lives of the province’s 94 million people have been upended by transport closures.

In Zhengzhou, the capital of Henan on the banks of the Yellow River, more than 200mm of rain fell in one hour on Tuesday, forcing the city to stop all subway train services.

Dramatic video shared on social media showed commuters waist-deep in murky floodwaters on a subway train and an underground station turned into a large, churning pool.

Trapped passengers cling to handrails in the flooded subway carriage

Henan is a major logistics hub but train services were suspended, while many highways were closed and flights delayed or cancelled.

Flooding in Zhengzhou in central China's Henan province

In Ruzhou, a city southwest of Zhengzhou, streets have been turned into torrents, sweeping away cars and other vehicles, footage on social media showed.

A rising Yi River also threatened to hit the Longmen Grottoes, a Unesco World Heritage site featuring millennium-old Buddhist statues etched into limestone cliffs near the city of Luoyang.

Like the Longmen Grottoes, the Shaolin Temple in Dengfeng city, famous in the West for its martial arts, has been temporarily shut.

Also in Dengfeng, an aluminium alloy plant exploded on Tuesday as water from a river surged into the factory.

At least 31 large and medium-sized reservoirs in the province have exceeded their warning levels.

From Saturday to Tuesday, 3,535 weather stations in Henan saw rainfall exceed 50 mm, of which 1,614 registered levels above 100 mm and 151 above 250 mm.

The highest was in Lushan city, which saw 498 mm of rain, according to the provincial weather bureau.

"This is the heaviest rain since I was born, with so many familiar places flooded," said an internet user in the inundated city of Gongyi on Chinese social media.

Rain is forecast to stop by Thursday.