SEOUL, June 22 (Reuters) - Two vessels operated by South Korea passed through the Strait of Hormuz after the U.S. and Iran signed a memorandum of understanding on a ceasefire agreement last week, Seoul's Ministry of Oceans and Fisheries said on Monday.

The vessels are sailing normally, but have not yet fully exited a high-risk zone, the ministry said, declining to disclose further details on the vessels.

The ships do not have South Korean crew on board and are not bound for South Korea, the ministry said.