Sofia, Bulgaria - Human remains were found aboard a vessel struck by a drone off the Romanian coast two weeks ago, said prosecutors Saturday in Bulgaria, where the vessel was being repaired.

"During debris-clearing operations, severely damaged human remains were discovered," the prosecutor's office in the eastern Bulgarian city of Varna said in a statement.

It added that DNA testing had been ordered to identify the victims.

It did not name the vessel, but said it was sailing under the San Marino flag – matching that of the Wine Trader, a chemical tanker hit on October 15 about 15 miles southeast of Sulina, at the mouth of the Danube.

Crime Multiple killed in shocking shooting in Poland with dozens injured, police say

The condition of the remains made it impossible to determine the exact number of bodies with certainty, a Bulgarian law enforcement source told AFP, saying there were "most likely six" victims.

Seven of the ship's 12 crew members had been reported missing following the strike, while five others were rescued.

Since early October, at least nine merchant vessels have been struck by drones off the Romanian and Bulgarian Black Sea coasts, leaving 34 people dead or missing.