A highway pile-up involving at least 30 cars killed 18 people in eastern China on Wednesday, local authorities said, leaving dramatic scenes of twisted and burnt-out wreckage and a towering column of black smoke.

Grisly footage from the aftermath in the city of Fuyang in Anhui province showed sedans violently crushed to around half their original size under large cargo trucks and blood stains on vehicle doors as the sound of people crying could be heard.

Police said another 21 people were injured including 11 severely in the latest horrific tragedy to strike China's accident-prone highways.

Officers said the brutal mash-up was caused by low visibility due to "fog", but China's notorious air pollution may have also played a role.

The Fuyang government had issued a heavy pollution alert for the area, advising residents to minimise outdoor activities.

The accident caused several of the vehicles to catch fire in a blaze that raged for more than two hours and left several cars completely charred.

Video of the aftermath on Chinese news websites showed one shocked-looking man sitting on the road next to a car while a dead body lay just a few metres (yards) away.

The local fire department said it dispatched 14 trucks and over 100 firefighters to the scene.

Deadly road accidents are common in China, where traffic regulations are often flouted or go unenforced.

China suffered more than 180,000 traffic accidents in 2015, killing 58,000 people, authorities said last year.

Violations of traffic laws were blamed for nearly 90 percent of accidents that caused deaths or injuries that year.

In August, at least 36 people were killed and 13 injured when a bus slammed into a wall at the mouth of an expressway tunnel in northern China, authorities said.