A Houthi militant attack on a Liberian-flagged cargo ship in the Red Sea killed at least two crew members and left the vessel without propulsion in the latest sign that the Tehran-backed group is once again escalating its maritime assaults in the vital trade route.

A Liberian delegation confirmed the deaths during a meeting of the International Maritime Organization. The Associated Press reported that three mariners had been killed, citing the European Union naval force.

"The vessel has sustained significant damage and has lost all propulsion,” the U.K. Maritime Trade Operations (UKMTO), a liaison between the U.K. Navy and commercial shipping, said on Tuesday. The Greek-owned vessel had sustained hours of attacks, including by propelled grenades and an approach by multiple boats, the group said.