By Kim Tae-gyu

SK Engineering and Construction (E&C), a subsidiary of SK Group, is undergoing a special tax audit for an unidentified reason, a source familiar with the issue said Thursday.

The action of the National Tax Service (NTS) is grabbing attention because it comes at a time when SK Chairman Chey Tae-won is suspected of having attempted to cover losses from his futures investments with corporate funds.

Watchers are guessing that the NTS might find some clues with regard to SK E&C before raiding the Seoul-based contractor, which frequently conducts intra-group transactions.

``NTS officials asked us to stop all work today (Thursday) and confiscated documents. They said they would visit again within a week,’’ said the source who asked not to be named. He also said that investigators were from the fourth bureau of the agency.

The NTS refused to confirm the tax audit, despite SK E&C’s comments that the probe is a regular audit.

If it is a regular one ― carried out every four or five years ― the first bureau is supposed assume the task. The fourth bureau is a specialized team that investigates alleged tax evasion by large firms.

When the fourth bureau takes action, the team typically has suspicions with substantive evidence, according to the source.

SK E&C did not confirm whether the investigators were from the first or the fourth bureau.