An abandoned tanker is believed to have sunk off the coast of Yemen after taking on water last month.
Naval and security sources told Reuters that a ship named as the Lavant has now disappeared.
The only vessel in shipping databases of the same name is a 7,700-dwt product carrier built in 1994.
There has been no AIS update from the ship for 224 days.
TradeWinds reported on 26 June that the crew of 19 was rescued by Sovcomflot's 111,682-dwt aframax NS Africa (built 2009) last week.
The vessel responded to a distress signal and picked up all the seafarers from a life raft after they abandoned the ship.
The Russian company said the seafarers were from India, Myanmar, Bangladesh and Indonesia.
The Lavant had reported flooding that could not be contained about 178 km off the southern Yemen coastal town of Nishtun, according to UK Maritime Trade Operations.
Security sources said an attack by Houthi forces was unlikely to have been the cause.
Two sources told Reuters the ship had suffered engine failure.
The vessel had been adrift for days. It was not clear if it was carrying any cargo.
Clarksons and Equasis list the last known operator as Glow Shipping Lines of the United Arab Emirates, which could not be contacted.
The crew was due to leave the NS Africa on arrival in Suez.
The ship was on a ballast leg back to Russia after delivering 730,000 barrels of Urals crude to an Indian refinery, according to Kpler ship tracking data.
