Mitsubishi Corp. said a rogue oil trader at its Singapore unit lost $320 million in unauthorized transactions disguised as legitimate hedges for customers.

The employee, a Chinese national working at Petro-Diamond Singapore Pte, has been fired and reported to police, Mitsubishi said in a statement, declining to name him. The trader, hired in November 2018 to handle oil business with China, “repeatedly” engaged in the unauthorized deals since January, disguising them to “look like hedge transactions,” the parent company said.