Yugoslavian the JRB steam tug Istra sighted on the Danube according to a CIA report dated 29 March 1955

An item dated 5 January 1955 reported the JRB (Jugoslovensko Recno Brodarstvo) steam tug Istra sighted on the Danube kilometre mark 1858 lying anchored with a tow of 4 JRB barges.

Source
The report was published on www.archive.org, document number CIA-RDP80-00810A006200800008-0