The latest attacks mark an escalation in the conflict between Iran and US-Israeli forces, raising the number of ships struck in the region since fighting began to at least 16.
Shipping in the Gulf and along the narrow Strait of Hormuz, which carries about a fifth of the world's oil, has come to a near-standstill since the US and Israel began strikes on Iran on February 28, sending global oil prices surging to highs not seen since 2022.
The ships targeted in late-night armed boat attacks in the Gulf near Iraq on Wednesday, local time, were the Marshall Islands-flagged Safesea Vishnu and the Zefyros, which had loaded fuel cargoes in Iraq, two Iraqi port officials said.
"We recovered the body of a foreign crew member from the water," one port security official said, as Iraqi rescue teams continued searching for other missing seafarers.
It was not immediately clear which ship that person was linked to.
Iran's Revolutionary Guards have warned that any ship passing through the Strait of Hormuz will be targeted.
US President Donald Trump has threatened to ramp up attacks on Iran if it continues to obstruct the strait.
The Thai-flagged Mayuree Naree dry bulk vessel was struck by "two projectiles of unknown origin" while sailing through the strait earlier on Wednesday, causing a fire and damaging the engine room, the ship's Thai-listed operator Precious Shipping said in a statement.
"Three crew members are reported missing and believed to be trapped in the engine room," Precious Shipping said.
"The company is working with the relevant authorities to rescue these three missing crew members," it said, adding that the remaining 20 crew members had been safely evacuated and were ashore in Oman.
Images provided by the Thai navy showed smoke pouring out of the back of the ship.
Iran's Guards said in a statement carried by the Tasnim news agency that the ship was "fired upon by Iranian fighters", suggesting the first direct engagement by the Guards who have previously fired missiles or drones.
The Japan-flagged container ship ONE Majesty also sustained minor damage on Wednesday from an unknown projectile 46 kilometres northwest of Ras Al Khaimah in the United Arab Emirates, two maritime security firms said.
Its Japanese owner Mitsui OSK Lines and a spokesperson for Ocean Network Express, its charterer, said the vessel was struck while at anchor in the Gulf and an inspection of the hull revealed minor damage above the waterline.
All crew are safe, they said, adding that the vessel remains fully operational and seaworthy. The owner said the cause of the incident remained unclear and was under investigation.
A third vessel, a bulk carrier, was also hit by an unknown projectile approximately 50km northwest of Dubai, maritime security firms said.
The projectile had damaged the hull of the Marshall Islands-flagged Star Gwyneth, maritime risk management company Vanguard said, adding that the vessel's crew were safe.
