Import-dependent South Korea has taken steps to mitigate the risks to its energy supplies since US-Israeli attacks on Iran in late February prompted Tehran to shut off access to the strait, now under a US blockade.

Seoul has sought new sources of oil and said this month that it would send five Korean-flagged ships to the Saudi Arabian Red Sea port of Yanbu to establish alternative routes.

The ministry announced on Friday the "first case of crude oil being transported into the country via the Red Sea, a detour, since the blockade of the Strait of Hormuz".

President Lee Jae Myung called it "a valuable achievement made by the relevant ministries moving as one team".

"I would like to express my gratitude to everyone who worked hard day and night despite difficult conditions, especially the sailors," he said on X.

Kang Hoon-sik, chief of staff to the president, said on Wednesday that South Korea had secured supplies of more than 270 million barrels of crude oil via routes unaffected by Hormuz crisis through the end of the year.

The figure is equivalent to more than three months of South Korea's oil needs based on last year's figures, Kang said.

The official recently returned from a trip to Kazakhstan, Oman, Saudi Arabia and Qatar in a bid to secure alternative fuel sources.