Yemen's Houthi militants are believed to have sunk a second ship, the Tutor, in the Red Sea, the United Kingdom Maritime Trade Operations (UKMTO) said on Tuesday.
The Greek-owned Tutor coal carrier was struck by missiles and an explosive-laden remote-controlled boat on June 12 and had been taking on water, according to previous reports from UKMTO, the Houthis and other sources.
"Military authorities report maritime debris and oil sighted in the (Tutor's) last reported location," UKMTO said in a security update.
The Tutor's manager could not immediately be reached for comment.
One crew member, believed to be in the Tutor's engine room at the time of the attacks, remains missing.
The Iran-aligned Houthis have been targeting commercial ships in the Red Sea region since November, in what they say are attacks in solidarity with Palestinians in Gaza.
The UK-owned Rubymar was the first ship sunk by the Houthis. It went down on March 2, about two weeks after being struck by missiles.
The UKMTO's report of the suspected Tutor sinking comes a week after the Houthis seriously damaged that Liberia-flagged ship, as well as the Palau-flagged Verbena, which was loaded with wood construction material.
Sailors from the Verbena abandoned ship when they were unable to contain a fire sparked by the attacks. The Verbena is now drifting in the Gulf of Aden and vulnerable to sinking or further assaults.
Since November, the Houthis have also seized another vessel and killed three sailors in separate attacks.
The Houthi drone and missile assaults have forced shipping firms to divert vessels from the Suez Canal trade shortcut to the longer route around Africa, disrupting global trade by delaying deliveries and sending costs higher.
U.S. and British forces on Monday conducted airstrikes targeting Yemen's Hodeidah International Airport and Kamaran Island near the port of Salif off the Red Sea in what appeared to be retaliation for last week's ship attacks.
By Adam Makary, Jaidaa Taha and Lisa Baertlein