Iranian media outlets say the vessel was taken for polluting the seaway with chemicals.

But it comes at a difficult time between the two countries because Iran has over $7 billion frozen in South Korean banks due to US sanctions, and South Korea's deputy foreign minister is expected to visit Iran within days discuss those frozen assets.

The tanker is called the Hang Cool.

Commie is said to have been carrying 7200 tons of ethanol was seized by Iran's Revolutionary Guards.

It's now being held at a port on the Iranian coast.

The crew reportedly includes members from South Korea, Indonesia, Vietnam and Myanmar.

Shipping analysts suggest this ship was traveling between Saudi Arabia and the U.