Four crew members of a Greek-operated bulk carrier have been killed in an attack by sea drones and speedboats off Yemen, an EU mission and a delegation from Liberia told a meeting of the UN shipping agency IMO on Tuesday.

The Eternity C, a Liberia-flagged vessel, was attacked on Monday evening off the coast of Hodeidah, maritime monitors reported. It was the second Red Sea attack in 24 hours after a recent period of relative calm.

The UK Maritime Trade Operations (UKMTO), run by the British Navy, said the ship sustained significant damage and lost propulsion after being hit by five rocket grenades.

It came after Sunday's attack on a Greek-operated ship, when the Magic Seas was hit by gunfire, drones and missiles, also in the Red Sea. Yemen's Houthi rebels claimed responsibility for Sunday's attack.

Previously, the Houthis relied on missiles, single-use drones or occasionally boat-launched rockets. Now, they have wired these elements into a multipronged “swarm” approach, with surface boats, aerial drones, missiles, and firearms all converging on a single target.

The Houthis have been attacking Israel and commercial vessels in the Red Sea and Gulf of Aden since the Gaza war broke out in October 2023. But the latest incidents are rare assaults in the strategic waters near Yemen, coming two months after the US announced a truce with the Houthis aimed at halting attacks on ships in the region.

In response, Israel has been carrying out strikes on Yemen. The Yemeni port city of Hodeidah was struck on Sunday night, along with the ports of Ras Isa and Salif and the Ras Al Khatib power station, the Houthi-run Al Masirah television channel reported. The Israeli military said it “struck and destroyed terror infrastructure belonging to the Houthi terrorist regime”.

“Among the targets were the ports of Hodeidah, Ras Isa and Salif,” the military said. It was the Israeli army's first attack on Yemen in about a month. The army also hit the Galaxy Leader ship docked at Ras Isa port, which was seized by the Iran-backed Houthis in late 2023.

Ambrey said early on Tuesday it had observed imagery that confirmed damage to concrete docks at Hodeidah following the Israeli strikes.

Additionally, two Barbados-flagged bulk carriers are thought to have suffered blast damage as a result of the attacks, Ambrey said in an advisory note, adding no injuries among the crews had been reported.

A UAE rescue mission brought the 22 crew members to safety.