A government delegation left for Iran on Thursday to negotiate an early release of the South Korean oil tanker and its crew seized by Iranian authorities earlier this week.

The delegation, led by Koh Kyung-sok, director-general of the foreign ministry's Africa and Middle Eastern affairs, boarded a plane early Thursday and is set to arrive in Iran via Qatar, foreign ministry officials said.

On Monday, Iran's Islamic Revolutionary Guards Corps (IRGC) seized the MT Hankuk Chemi carrying 20 crewmembers, including five South Koreans, due to environmental pollution allegations. The ship is currently at a port in Bandar Abbas, a city on Iran's southern coast.

"I plan to meet my counterpart at the Iranian foreign ministry, and will meet others through various routes if that will help efforts to address the ship's seizure," Koh told reporters at Incheon International Airport, west of Seoul.

Iran has claimed that the seizure took place due to "technical issues" and the matter will be addressed in line with its judicial process. The ship's operator has denied the oil pollution allegations.

Seoul's First Vice Foreign Minister Choi Jong-kun is also expected to travel to Iran early next week to discuss the seizure and other bilateral issues.

On Wednesday, the South Korean Embassy in Iran sent three staffers to meet a sailor of the seized ship and found that all 20 crew members are safe and in good shape, according to the foreign ministry.

The seizure came amid lingering tensions between Seoul and Tehran over the latter's money frozen at South Korean banks under US sanctions.

Tensions between the United States and Iran also rose as Tehran began a uranium enrichment process and marked the first anniversary of the death of an Iranian general killed in a US drone attack. (Yonhap)