McDonald's South Korean offices raided

South Korean prosecutors raided McDonald's Seoul office, as well as those of three partner companies, on Wednesday as part of a probe into allegations that the US fast food giant had been undercooking its meat, causing many customers severe illnesses.

Investigators searched the main office of McDonald's Korea in central Seoul and its patty suppliers to confiscate documents and other evidence, the Seoul Central District Prosecutors' Office said.

In July, a McDonald's customer had filed a complaint against the firm, saying her four-year-old daughter had been diagnosed with haemolytic uremic syndrome, otherwise known as hamburger disease, after one of the company's hamburgers caused her irreversible kidney damage in 2016.

Complaints were also filed by the families of four more children that had become sick after eating McDonald's burgers.

In August, diners at one of the chain's locations in Jeonju to the south-west of the country reported stomach aches and high fever after eating bulgogi burgers, leading McDonald's to temporarily halt sales of the burgers to determine the cause.

At the time, the firm claimed to be cooperating with a South Korean government investigation into the possible food contamination case.