A welder in western China was killed when a mobile phone battery exploded in his chest pocket, state media said Wednesday.

The official Xinhua News Agency said that welder, Xiao Jinpeng, died on June 19 while working at the Yingpan Iron Ore Dressing Plant in Gansu's Jinta county.

Xinhua quoted Bai Shixiong, an official with the county public security bureau, as saying a Motorola cell phone in Xiao's chest pocket suddenly exploded, and he died at a local hospital after emergency treatment failed.

However, a Beijing spokesman for Schaumburg, Ill.-based Motorola Inc. said it was "highly unlikely" that one of the company's products was to blame and questioned whether the man was using a fake Motorola cell phone or battery.

"We are aware of an accident that occurred in Gansu at a welding operation," said Yang Boning, a press officer for Motorola in Beijing. "Up to now, preliminary evidence suggests it is highly unlikely that a cell phone caused this accident. We are working with the Chinese authorities to determine and investigate the root cause."

A team of Motorola employees was in Gansu to help local authorities investigate, he said.

Colleagues said Xiao collapsed when the cell phone suddenly exploded after apparently being exposed to high temperatures, Xinhua said. Xiao suffered broken ribs and rib fragments pierced his heart, the report added.