The explosion in the Kerch Strait that killed at least 14 crew members during a ship to ship transfer between LPG vessels happened in an area known to be used by vessels carrying out illegal fuel transfers.
The 4,811-dwt Maestro (built 1990) and the 4,444-dwt Candy (built 1992) were anchored off Cape Takhil in the Crimea, where sources say transfers regularly take place to avoid trade sanctions imposed on Russia and the Crimea.
The blast occurred on Monday evening.
Local news sources cited the Ukrainian ministry of temporary occupied territories and displaced persons as saying both vessels have been listed by the US Office of Foreign Assets Control (OFAC) as delivering cargo to Syria between 2016 and 2018.
Both vessels are listed as owned by Milano Shipping and are registered in Tanzania. It appears neither ship had P&I cover.
The 31 crew involved are mainly from India and Turkey. Five crew members are understood to have jumped into the sea and are still missing.