(ATTN: UPDATES throughout; ADDS photo)
SEOUL, Jan. 4 (Yonhap) -- The operator of a South Korean-flagged oil tanker seized by Iran Monday denied that the vessel polluted waters in the Persian Gulf.
An official from the operator, DM Shipping, based in the southeastern city of Busan, said that the Iranian authorities contacted the vessel, MT Hankuk Chemi, as it sailed in high seas and that there was no pollution.
Iran's Islamic Revolution Guards Corps boarded the ship at around 4:30 p.m. and demanded the ship face examinations in Iranian waters, the official said.
"(The ship's captain) asked why we have to go and be examined and did not get any answer," he added.
Seoul's foreign ministry confirmed that the ship, which was travelling in waters near Oman, is moving towards Iranian waters upon Iranian authorities' request. It said that South Korea's anti-piracy Cheonghae Unit is moving toward the scene.
"The foreign ministry and the South Korean embassy in Iran have found that the crews are safe, and are requesting the early release of the ship," the ministry said in a statement.
The defense ministry said that it will deal with the seizure in cooperation with the ministries of foreign affairs and fisheries, and a multinational naval force operating in nearby waters.
The vessel was carrying 20 crewmembers -- 5 Koreans, 11 Myanmarese, two Indonesians and two Vietnamese.
The incident came as tensions have been rising between the United States and Iran, with Tehran beginning uranium enrichment up to 20 percent at an underground facility and marking the first anniversary of the death of a general killed in a U.S. drone strike.
South Korea has been facing a diplomatic quandary between the U.S., its core ally, and Iran, a key trade partner in the Middle East.
Yoon-Biden summit likely to focus on broadening alliance amid N.K. threats, China's assertiveness: experts
Yoon's first summit with Biden to focus on N. Korea, economic security
N. Korean leader Kim ramps up nuclear threat, alludes to more aggressive doctrine
ICBM launch puts Yoon's N. Korea policy to test
Concerns grow over possible North Korean nuke test