Customs officers at the Tan Cang Cai Mep-Thi Vai Port in the southern province of Ba Ria-Vung Tau found a 17-container shipment suspicious and decided to carry out a thorough inspection on Tuesday.
Inside one of the containers, they found four large sacks containing 119 kilograms (262 pounds) of a white powder among the scrap steel.
Tests found that the powder was high-quality cocaine, putting the total value of the haul at VND700-800 billion ($30.2-34.5 million).
According to logs, the Liberia-flagged cargo ship, Mark Shenzhen, which transported the scrap steel shipment, began its voyage from Trinidad and Tobago two months ago and docked in Panama for half a month before arriving in China on July 15.
The ship then berthed at the Tan Cang Cai Mep-Thi Vai Port on Tuesday morning, where it unloaded the scrap steel containers before leaving for Singapore immediately afterwards.
Authorities have identified the shipment's owner as Singaporean company Stamcorp International Pte. Ltd. and its recipient as local firm Pomina Steel 2. The seal on the container, however, did not match documents provided by the shipment's owner.
In a press release issued on Wednesday, Pomina Steel JSC. confirmed that its subsidiary Pomina Steel 2 had signed a contract to buy 355 tons of scrap steel from Stamcorp International but denied any knowledge of the cocaine.
The company stressed that it "does not import prohibited goods" and said it is working with the shipment's owner and the authorities to clarify this issue.
Ba Ria-Vung Tau police have said that this is the largest-ever drug haul in the province.
Vietnam has some of the world’s toughest drug laws. Those convicted of possessing or smuggling more than 600 grams of heroin or cocaine or more than 2.5 kilograms of methamphetamine could face the death penalty. The production or sale of 100 grams of heroin or 300 grams of other illegal narcotics is also punishable by death.