Iran said it was behind one of the attacks, but made no comment on the other.

Oil-rich Iraq has long been a proxy battleground between the United States and Iran, and saw itself dragged straight into the Middle East war after Israel and the US attacked Iran on February 28.

Within hours, warplanes and missiles from every direction filled its airspace, and on Thursday, an attack on two oil tankers killed at least one crew member, an Indian national.

Farhan Al-Fartousi, from Iraq's General Company for Ports, told AFP that "all crew members of the two tankers were rescued," adding that the 51 workers were in good condition.

The attack killed at least one crew member, said Fartousi.

India's embassy in Iraq said on Thursday an Indian national had died in the attack, with 15 other Indian crew members evacuated.

The attack occurred roughly 50 kilometres (30 miles) from Iraq's coast.

Iraq's State Organisation for Marketing of Oil (SOMO) said that two tankers are Maltese-flagged oil ZEFYROS and the SAFESEA VISHNU which was sailing under the Marshall Islands flag.

Iran's Revolutionary Guards said Thursday they had struck the Marshall Islands-flagged ship Safesea, which they claimed was US-owned, in the north of the Gulf "after ignoring and not complying with warnings and alerts".

The Strait of Hormuz, a 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 the war continues.

Iraq's crude production and exports have plunged since the Hormuz disruption, and the oil ministry has said "the safety of navigation in international maritime corridors and energy supply routes must remain free from regional conflicts."

- Oil-dependent -

Iraq is a founding member of the OPEC cartel, and crude oil sales make up 90 percent of the country's budget revenues.

The tankers' attack came 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.

After decades of conflicts, Iraq remains volatile with increasingly influential armed groups operating outside the state's control.

When war broke out, Iran-backed armed groups in Iraq were the first targets of strikes blamed on the US and Israel.

On Thursday, two senior Iraqi security officials told AFP that at least nine fighters belonging to the US-blacklisted Harakat Ansar Allah al-Awfiya were killed in airstrikes on their base near the Iraqi-Syrian border.

The security sources did not identify who was behind the attack, but the Iran-backed group blamed Israel and the US.