South Korean authorities have released a Russian vessel that Moscow said was being held in the South Korean port of Busan, the TASS news agency quoted the Russian Embassy in Seoul as saying.

Russia's Foreign Ministry on Monday said the Sevastopol had been seized illegally and demanded its immediate release.

A vessel named Sevastopol was one of six Russian-flagged vessels targeted by U.S. sanctions for alleged breaches of United Nations restrictions on dealings with North Korea.