The US attacked a key Yemen oil port controlled by the Houthis overnight and killed dozens of people, according to the Iran-backed militants, raising the specter of a widening conflict in the Middle East.

The US says the attack on the Red Sea coast aimed to restrict supplies and funds for the Houthis, who called it a war crime.

U.S. strikes on Yemen's Ras Isa fuel terminal on the Red Sea coast have killed at least 74 people in the deadliest attack since the U.S. started its bombing campaign against the Houthis last year, according to the Houthi-run health ministry.