The nation's tax authorities are investigating four South Korean firms allegedly involved in the illegal trade of North Korean coal last year in violation of the U.N. Security Council (UNSC) sanctions against the North.
An official of the Korea Customs Service said, "We are conducting an investigation and will decide whether to refer this case to the prosecution."
The official said two shipping firms and two financial firms are being investigated, without revealing their names.
If the allegations are true, they would be a violation of UNSC sanctions that ban North Korea from exporting coal and firms involved in the case will be placed on a sanctions list.
"We cannot provide further details about the matter as there is an ongoing investigation," the official added.
Panama and a Sierra Leone flagged vessels brought 9,000 tons of coal to the South Korean ports of Incheon and Pohang in October last year, the unification ministry said.
Under U.N. Resolution 2371 adopted by the Security Council in August last year, transfer of North Korean minerals, such as coal, are prohibited.
Regarding the media reports that there were four South Korean firms involved in the issue, the foreign ministry released a statement that government officials are conducting an investigation on the North Korean coal issue and will take all necessary measures.
It said that "(an) import company is suspected of importing North Korean coal. The U.S. government didn't express concern about the issue and we are in close cooperation with the U.S. to faithfully implement the UNSC resolutions."
Recently, the VOA reported North Korea's coal transferred to the Russian port of Kholmsk was reloaded and sent to Incheon and Pohang on Oct. 2 and Oct. 11, 2017, respectively.