South Korea to send delegation to Iran over oil tanker seizure

South Korea will send a government delegation to Iran "at the earliest possible date" to negotiate the release of a seized oil tanker and its crew, Seoul's foreign ministry said Tuesday.

Iran's Revolutionary Guards said Monday it had seized the South Korean-flagged Hankuk Chemi in Gulf waters "due to the repeated infringement of maritime environmental laws".

It said the vessel was carrying 7,200 tonnes of "oil chemical products".

The arrested crew were from South Korea, Indonesia, Vietnam, and Myanmar, the elite force said on its website Sepahnews, without giving further details.

"A delegation... will be dispatched to Iran at the earliest possible date to try to resolve the matter through bilateral negotiations," foreign ministry spokesman Choi Young-sam said.

Separately, South Korea's vice foreign minister Choi Jong-kun will go ahead with a planned three-day trip to Tehran early next week, the spokesman added.

The vice minister's visit had been arranged prior to the seizure, as Tehran seeks the release of billions of dollars held in Seoul under US sanctions.

South Korea's foreign minister Kang Kyung-wha did not comment on speculation that Iran seized the ship in a bid to pressure Seoul to unlock Iranian assets.

"We need to verify the facts first and ensure the safety of our crew," Kang told reporters.

"We are making diplomatic efforts for an early release," she added.

Seoul's defence ministry said Choi Young, a destroyer carrying members of South Korea's anti-piracy unit, arrived in waters near the Strait of Hormuz and was "carrying out a mission to ensure the safety of our nationals".

The seizure follows days of heightened US-Iranian tensions marked by the first anniversary of the US assassination of Iran's revered military commander Major General Qasem Soleimani in a Baghdad drone strike.