Yemen's Iran-aligned Houthis say they have fired missiles at two more vessels in the Red Sea, causing damage to the ships.
The Houthis have been targeting commercial vessels with drones and missiles in the Red Sea since mid-November, in what they describe as acts of solidarity with Palestinians against Israel in the Gaza war.
The group's military spokesman said it had fired naval missiles at the Star Nasia and Morning Tide, identifying the Marshall Islands and Barbados-flagged ships, respectively, as American and British.
The Greek-owned Star Nasia, managed by Star Bulk Carrier, was damaged by an explosion, a Greek shipping ministry official said, adding that its crew were not injured.
It is unclear whether the explosion was caused by a sea mine or a rocket, the official added.
In a televised speech, Houthi leader Abdul Malik al-Houthi said the group will "seek to escalate more and more if the barbaric and brutal aggression against Gaza does not stop, along with the siege of the Palestinian people from whom they deny aid and medicine."
Diplomatic efforts were "being made to try and find a climb down for the Houthis that would enable [the] situation to improve and to move away from the kinetic aspect" of the Red Sea crisis, US Special Envoy for Yemen Tim Lenderking said on Tuesday.
Mr Lenderking, in recorded comments to the Middle East Institute, also said "we need to see serious de-escalation in Gaza" and that Secretary of State Antony Blinken was working very hard on that.
The United Kingdom Maritime Trade Operations (UKMTO) agency and British maritime security firm Ambrey said the southbound Greek-owned bulk carrier Star Nasia had been targeted while heading through the Maritime Security Transit Corridor about 53 nautical miles south-west of Aden, en route from the US to India.
Maritime monitoring service TankerTrackers.com said the vessel was carrying US coal to India.
Morning Tide suffers damage
Ambrey said the Morning Tide, a Barbados-flagged general cargo ship owned by a British company, had suffered damage from an unmanned aerial vehicle (UAV) while sailing south through the Red Sea.
No injuries were reported. The ship performed evasive manoeuvres and continued its journey, Ambrey said.
The owner of the Morning Tide, British firm Furadino Shipping, told Reuters the ship was currently sailing without problems, but gave no further information.
LSEG ship-tracking data showed the Morning Tide was heading south through the Red Sea after navigating the Suez Canal on Friday. Its most recent signal shows it sailing out of the Red Sea through the Bab al-Mandab Strait.
The United Kingdom Maritime Trade Operations (UKMTO) agency had reported just after midnight GMT on Tuesday that a projectile had been fired at the port side of a ship located 57 nautical miles west of Hodeidah and that a small craft was seen nearby.
The projectile passed over the deck and caused slight damage to the bridge windows, but the vessel and crew were safe and proceeded on the planned passage, UKMTO added.
The Red Sea attacks have disrupted global shipping and forced firms to re-route to longer and more expensive journeys around southern Africa and stoked fears that the Israel-Hamas war could spread to destabilise the wider Middle East.
The United States and Britain began striking Houthi targets in Yemen last month in retaliation for the attacks on Red Sea shipping.
Reuters