The Incheon Main Customs has grilled her on the allegations, but she has persistently denied all the charges. The customs authority said that because she could tamper with incriminating evidence it has asked the regional prosecutors office to obtain an official warrant.

Earlier, the customs authorities confiscated 2.5 tons of suspected smuggled goods that may have belonged to Cho from a Korean Air subcontractor and company officials' residences. 

The disgraced Cho has also underwent interrogation by the immigration office in May over suspicions that she and members of her family had illegally hired more than a dozen housekeepers from the Philippines.

The probe into her alleged smuggling is the latest in a spate of ongoing investigations into the Cho family, which controls a hotel and logistics conglomerate.

Her mother, Lee Myung-hee, is on the verge of arrest over multiple aggravated assault charges -- a Seoul court is reviewing her arrest warrant on the same day. Her younger sister has been subject to allegations of assault and her brother faces suspicions over unfair acceptance into a university with ties to Hanjin. (Yonhap)