The Bulgarian tug Kiril Popov according to a CIA report dated 8 September 1950

An item reported that the Bulgarian shipping company Bulgarian River Navigation (BRP) at Ruse possessed the tug Kiril Popov with a tonnage of 1.000 ton, a crew numbering 15 men and 2x800hp horsepower with one heating chamber. Tow capacity 6 barges upstream the river. Largest Bulgarian tug.

Source
The report was published on www.archive.org, document number CIA-RDP82-00039R000100080032-8