A couple accused of burying their four-day-old newborn on a hill in the South Gyeongsang provincial city of Geoje have been arrested.

According to the Gyeongnam Provincial Police on Friday, a man in his 20s and his common-law wife in her 30s were apprehended for burying their newborn son in a plastic bag.

They are suspected of concealing the baby's dead body after he died in a residential unit last September, just four days after his birth at a medical facility, with the couple reportedly testifying that they found their son dead after they woke up.

The police arrested them late Thursday, after receiving a report from administrative authorities in the provincial county of Goseong, where the couple's registered address is located.

Investigators have also begun a search to excavate the newborn's body.