A rice ball purchased at a Lawsons convenience store in Northern Japan held a gruesome surprise for one woman consumer last Friday; a severed fingertip.

The woman took the half-inch chunk of flesh to the doctor after she bit into a Korean bibimbap snack, where it was identified as a fingertip.

Lawsons spokesman Takashi Fujii apologised for the incident. "We'll make sure this sort of thing doesn't happen again," he said.

It later transpired that the fingertip belonged to an employee of food company Nihon Fresh Delica, which produced the bibimbap, a spicy mix of rice, vegetables and red pepper paste.