A fast-moving sandstorm has hit the Chinese city of Zhangye with a 100-metre-high sand wall.

Winds above 60 kilometres per hour whipped up sand and dust from the nearby Gobi Desert, quickly engulfing the city of 1.2 million people.

The so-called sand wall moved on the city — in the north-western Gansu province — within five minutes, reducing visibility to less than 10 metres.

Local authorities activated an emergency response plan, while local traffic police conducted two-way patrol on the expressways.

The traffic police directed the vehicles to the service area or toll stations and warned the passing vehicles to slow down and keep a safe distance.

APTN/ABC