South Korean First Vice Foreign Minister Choi Jong-kun left for Iran Sunday to seek the release of an oil tanker and its crew that were seized by Iranian forces in the Persian Gulf last week.

Choi left early Sunday and was to arrive in Tehran via Doha the same day. He is expected to meet with counterparts and other high-level officials at the Iranian Foreign Ministry to negotiate the return of the ship and its crew members, along with a government delegation that has already been in Tehran since Thursday.

Seoul has been scrambling to respond since Jan. 4, when Iran’s Islamic Revolutionary Guard Corps seized the oil tanker MT Hankuk Chemi and its 20 crew, citing “environmental and chemical pollution concerns.”

The vessel is currently held at Bandar Abbas, the port city on Iran’s southern coast, and the South Korean Foreign Ministry has confirmed that all sailors on board -- 11 from Myanmar, five Koreans, two Indonesians and two Vietnamese -- are safe.

“I am a little relieved to know that the crew is safe, but the situation is serious,” Choi told reporters at Incheon Airport before boarding his flight. “I hope to hold in-depth talks with key officials, whether it’s about consular issues or other major issues between Korea and Iran.”

Observers say the negotiation for a swift release of the tanker is not going to be easy, as Seoul and Tehran are at odds over the grounds for the seizure. Iran says the seizure is due to the vessel repeatedly violating environmental laws and would deal with the matter within the legal framework, while the vessel’s Busan-based operator flatly denied water pollution allegations.

Also Iran has stressed that Choi’s visit, which was arranged prior to the incident, “has nothing to do” with the seizure of the ship, but is aimed to discuss Iran’s frozen funds in Korean banks.

There has been simmering tension between Seoul and Tehran over about $7 billion in revenue from oil sales frozen in Korean banks since 2019 due to sanctions reimposed on Iran by the Donald Trump administration, after Washington’s unilateral decision to withdraw from the 2015 nuclear accord.

The timing of the seizure, which comes as the two sides and the US are discussing the funds, has raised speculation that the latest action was made to gain leverage and pressure Seoul into releasing the money.

Iran has been demanding Seoul grant access to the funds for some time, with the two sides and the US in talks to use part of the money to purchase COVID-19 vaccines and medical equipment for Iran.

A Foreign Ministry official said the negotiations to provide vaccines and equipment to Tehran are underway, but declined to disclose the amount.

In regards to the frozen fund discussion, Choi said the trip will be an opportunity to hear what the Iranian government wants, and to distinguish what Korea can and cannot do, as well as what needs to be consulted with the US.

By Ahn Sung-mi (sahn@heraldcorp.com)