The death of a 33 year-old South Korean quarry worker attributed to an apparent mobile phone explosion was actually caused by a co-worker.

The victim's colleague, Kwon Young-sup, originally told police and the media that he heard an explosion and found the man's body with the phone still burning.

Kwon has since confessed that he lied about the discovery to cover up a workplace accident, and has been charged with manslaughter.

"The co-worker confessed to us last night that he had actually hit him by accident and lied about the mobile phone exploding," said a police official at the Cheongju Heungdeok police station.

Reports suggest that Kwon unintentionally hit the victim while reversing a 15-ton hydraulic drill rig, pinning the victim to a rock face and killing him.

It is unclear whether the phone caught fire owing to the intense pressure or whether Kwon set it ablaze as part of the cover up.

Many reports identified the phone as an LG model, and the company has been quick to point out that the lithium-ion polymer batteries used in LG handsets have been approved for consumer use by a number of independent testing agencies.

LG now feels suitably vindicated. "LG rigorously tests all the products for functionality, design and safety," the firm said in a statement.

"LG is fully committed to providing the best products with uncompromising quality under all circumstances."