Media playback is unsupported on your device Media caption Amateur footage shows smoke billowing from the scene, as John Sudworth reports

An explosion at a factory in eastern China has killed at least 68 people, according to Chinese state media.

Almost 200 people were injured in the blast in Kunshan, a city in the eastern province of Jiangsu, China's official Xinhua news agency said.

Pictures posted online showed people with burns sitting on the ground outside a factory complex from which black smoke was billowing.

Xinhua said five company employees had been detained.

The factory belonged to the Kunshan Zhongrong Metal Products company.

The company manufactures car parts and employs about 450 workers. Its clients include US giant General Motors, CCTV reported.

Image copyright EPA Image caption The walking wounded waited for help outside the still burning factory

Image copyright Reuters Image caption More than 200 factory workers were said to be on the site at the time of the explosion

State media reports say that explosion took place inside a wheel hub polishing workshop and that 264 workers were at the site at the time of the explosion.

Xinhua said 44 people had died immediately and the total of injured stood at 187.

Initial reports suggested the explosion, which was heard several kilometres away, occurred when a flame was lit in a dust-filled room.

Glass was shattered up to 500 metres away.

Image copyright Reuters Image caption A victim is rushed to hospital in Kunshan

Kunshan is about an hour's drive from Shanghai, where some of the injured were taken for treatment. Others were taken to Suzhou.

One doctor on the Weibo microblog account of CCTV said: "In my 20 years of work, I've never seen so many patients with burns on over 80% of their bodies."

Industrial accidents are relatively common in China, says the BBC's John Sudworth in Shanghai, although figures show safety in some industries has been improving in recent years.

Some 119 people died in a fire at a poultry plant in northern Jilin province in June last year.