An anonymous actor has threatened to disclose the personal information of Coupang customers unless the e-commerce giant strengthens its security.

The Cybercrime Investigation Division of the Seoul Metropolitan Police Agency said Monday it is investigating an email that Coupang received from an account claiming to possess the company's customer data and threatening to release it to the media.

Police said the email did not include any monetary demands.

Coupang had announced on the 18th that personal information tied to 4,500 customer accounts had been exposed, then revised the figure on Saturday to 33‑point‑seven million.

Investigators are looking into whether the anonymous sender is also responsible for that data breach.

Police said that, although some have raised suspicions that a former Coupang employee leaked the information, they are keeping multiple possibilities open.