Farhan Al-Fartousi, from Iraq's General Company for Ports, told state television that one crew member had been killed and 38 rescued while the "search continues for the missing."

He did not specify the crew members' nationalities or provide details on who was behind the attack, but said that one of the two ships was registered under a Maltese flag.

The Iraqi government's media cell told national news agency INA that "two tankers were subject to sabotage."

The Strait of Hormuz -- the waterway carrying a fifth of the world's oil -- remains closed to almost all oil tankers, and Iran has vowed that not one litre of oil would be exported from the Gulf while its war with the United States and Israel continues.

US President Donald Trump said Wednesday that US forces have struck 28 Iranian mine-laying vessels more than a week into the Middle East war.

Images of a ship at sea with plumes of smoke rising from a huge fire, were broadcast by state television channel al-Ikhbariya. AFP could not verify the images.

An employee at Iraq's Basra oil terminal told AFP that it was unclear "whether it was a drone attack or explosive-laded boats".

The attack in Iraq comes just hours after the US embassy in Baghdad warned that Iran and Tehran-backed Iraqi armed groups might target US-owned oil facilities in Iraq.