Posco, South Korea's largest steel mill, will be subject to 7.02 percent anti-dumping duties, while those shipped by other companies will face 19 percent tariffs.

The galvanized steel products that have been coated to prevent rusting are used by carmakers, electronics companies and those making ventilation ducts. Of the over 60,000 tons of steel products exported to Vietnam annually, half are made by Posco, business data showed.

Kotra's Hanoi office said that local authorities have been investigating unfair dumping allegations since March 2016 onwards and handed out a preliminary injury determination last September. 

It said the country has been trying to cope with a ballooning trade deficit in the steel sector that reached $6 billion in 2016 as well as excess capacity that is hurting Vietnamese steel mills.

"The government here has been moving to protect local companies making steel," said a source who declined to be identified. He pointed out that last year alone Vietnam engaged in three separate cases of restricting steel imports. (Yonhap)