SEOUL: South Korea and Iran have been unable to reach an agreement over the seizure of an oil tanker by Iran’s Revolutionary Guard a week ago, according to diplomats in Seoul on Monday.

A day earlier, Vice Foreign Minister Choi Jong-kun arrived in Tehran to address the release of the South Korean-flagged MT Hankuk Chemi, which was captured by the Iranian troops near the strategic Strait of Hormuz. Choi’s visit followed a trip by a delegation led by Koh Kyung-sok, director-general of the ministry’s African and Middle Eastern affairs.

Despite the back-to-back visits, however, the Iranian authorities were blunt about Seoul’s request for the release of the ship that was carrying 20 crew members, including five Koreans, while pressing Seoul to unlock $7 billion in funds frozen amid US sanctions, a Korean ministry official told reporters on condition of anonymity.

Choi held a meeting with Iran’s Deputy Foreign Minister Abbas Araghchi upon arrival, making a strong request for the swift release of sailors and the vessel, the official said.

“Vice minister Choi renewed his call for Iran to release a seized oil tanker and its sailors,” he said. “He also urged Iran to offer evidence to back its claim that the vessel polluted the sea.”

Iran repeated, however, its claim that the ship was captured due to “technical issues” related to a breach of environmental rules and instead called for Seoul’s release of frozen funds, according to the official and Iran’s state media. “The freezing of Iran’s foreign exchange resources in Korea is more due to a lack of political will on the part of the Korean government than the US sanctions,” the Iranian vice foreign minister was quoted by the Islamic Republic News Agency (IRNA) as saying.

The Iranian diplomat said that Seoul “should refrain from politicizing the issue and from fruitless propaganda and allow the legal proceedings to proceed,” Iran’s state TV reported.

In a report submitted to the National Assembly on Jan. 6, Seoul’s Foreign Ministry hinted that it was preparing to take legal action against the Islamic Republic over the seizure of the tanker.

“As long as there is no demonstration of ‘an act of deliberate and grave contamination’ that would disqualify the ship’s innocent passage, we find that no violation of international law has occurred,” the report said.

Sung Woo-rin, a lawyer at law firm DR & AJU, said Iranian troops clearly violated international law.

“A tanker normally has a dual hull structure so that there is little chance of oil leakage, except for special cases such as a collision between ships,” the lawyer said. “Should delivery be delayed due to the seizure of a ship, the ship’s owner would be able to claim damages.”

Since a legal dispute could result in the protracted capture of the vessel, she said, diplomacy was the best way for the two governments to resolve the issue.

The seizure of the Hankuk Chemi followed Iran’s complaint last month about the difficulty of transferring money from Seoul to purchase coronavirus vaccines.

Iranian assets worth $7 billion in two Korean bank accounts were frozen after the Trump administration withdrew from the nuclear deal with Teheran in 2018.

In an effort to end the impasse, Seoul and Teheran discussed using the frozen money to purchase $1 billion of medical equipment, while Iran also requested the use of $10 million or more from the unlocked assets to buy vaccines from the global vaccine procurement facility COVAX.