South Korea's First Vice Foreign Minister Choi Jong-kun has departed for Iran to negotiate the early release of the South Korean oil tanker and its crew seized by Iranian authorities last week.

Choi boarded a plane early Sunday and is set to arrive in Iran via Qatar. He is expected to join the South Korean delegation that arrived earlier in Tehran and meet with his counterpart and other high-level officials at the Iranian Foreign Ministry.

Departing for the trip from Incheon International Airport, Choi told reporters that he was relieved to know that the crew is safe, but the situation is serious.

The vice minister plans to place top priority on securing the release of the tanker and its crew, while discussing the issue of Iranian funds frozen in South Korea under United States sanctions.

Iran reportedly requested South Korea to allow the use of the frozen money to purchase medicine, medical equipment and COVID-19 vaccines.

Choi said that Iran is demanding South Korea allow the use of the frozen funds, adding he would hear once again what the Iranian government wants and to distinguish what Seoul can do and cannot do regarding the seized funds.

On Monday, Iran's Islamic Revolutionary Guards Corps seized the MT Hankuk Chemi carrying 20 crew members, including five South Koreans, citing environmental pollution. The ship is currently at the port of Bandar Abbas, a city on Iran's southern coast.