The crew of a Belize-flagged, British-registered cargo vessel have abandoned ship off Yemen after it was hit by missiles fired by the Houthi movement.
The Rubymar was in the Gulf of Aden and nearing the Bab al-Mandab Strait when it was struck, security firms said.
A Houthi military spokesman claimed that the ship suffered "catastrophic damage" and was at risk of sinking.
The UK condemned the "reckless attack" on the Rubymar and said allied naval vessels were "already on the scene".
It is one of the most damaging attacks yet carried out by the Iran-backed Houthis, and is the latest evidence that Western efforts to deter them are yet to succeed.
The Houthis have launched dozens of missiles and drones at merchant vessels and Western warships in the Red Sea and Gulf of Aden since mid-November, in what they say is a show of support for the Palestinians in the war between Israel and Hamas in the Gaza Strip.
The attacks have prompted many shipping companies to stop using the critical waterway, which accounts for about 12% of global seaborne trade.
US and British forces began carrying out air strikes on military targets across Houthi-controlled western Yemen in response last month.
On Sunday night, the UK Maritime Trade Operations (UKMTO) agency said it had received a report of an incident from an unnamed ship about 35 nautical miles (65km) south of the Yemeni Red Sea port of Mocha.
The master had reported "an explosion in close proximity to the vessel resulting in damage" at about 23:00 local time (20:00 GMT), it added.
Early on Monday, the agency cited military authorities as reporting that the crew abandoned the vessel following an attack.
"Vessel at anchor and all crew are safe," it said. "Military authorities remain on scene to provide assistance."
British maritime security firm Ambrey separately reported that a Belize-flagged cargo ship had come under attack in the Bab al-Mandab Strait on Sunday as it sailed northwards.
