A crude oil spill from a tanker that ran aground near a natural reserve in Oman has created an oil slick covering an area of about 390 square kilometers and has spread up to seven kilometers from the coast. Oman’s Environment Agency announced this on Monday.

The tanker “Carolyn Bazangy” was transporting nearly one million barrels of Russian oil to Asia and encountered a problem on June 8 (Khordad 18) near the coasts of Yemen.

Two maritime security sources said initial assessments indicate that an explosion occurred on the vessel. No side has taken responsibility.

The tanker is on sanctions lists related to Russia and is part of a fleet that Moscow uses to circumvent sanctions.