Image caption A Foxconn spokesman said the situation was under control and the blast was being investigated

An explosion at a Chinese factory owned by Foxconn has killed three people and injured 15.

The incident happened on a production line for Apple's iPad 2 in Chengdu in the south-western province of Sichuan, according to local media reports.

It is unclear whether production of the iPad will be disrupted.

The Taiwanese manufacturer was quick to state the incident was an accident and police have ruled out foul play.

'Toxic smoke'

The explosion, which happened at about 1920 Beijing time (1220 GMT), has been brought under control, according to Foxconn spokesman Qian Ding.

He said the reason for the explosion, as well as the financial cost and the number of injured, were still being investigated.

Witnesses were reported by the China News Agency as saying they saw lightning strike the building shortly beforehand.

Chinese media also reported that fleeing workers had been warned of the risk of a secondary explosion.

However, other local media reports suggested the building's central air conditioning system might have been the cause.

The incident reportedly occurred in the polishing section of the factory and involved an explosion of ultra-light dust.

Foxconn staff told local media that there were hundreds of workers at the site when the accident occurred.

Security guards are reported to have told evacuees that smoke from the explosion was toxic.

Troubled history

The company has contacted its Taiwanese chief executive, Guo Taiming, who is now said to be on his way to Chengdu.

Foxconn has had a troubled recent history in China, with at least 13 employees dying in apparent suicides last year.

The Taiwanese firm is Apple's main manufacturing contractor, producing many different items, including the iPad 2.

The latest version of the iPad was already facing production difficulties due to strong demand and disruption to some parts manufacturers by the earthquake and tsunami which struck Japan in March.

It is unclear how reliant Foxconn is on the Chengdu plant for production of the tablet computers, as it has been reported that the bulk of output was actually being provided by a separate factory in Shenzhen.