British tanker Luxor visited Black Sea according to a letter of the German naval attaché at Istanbul dated 22 December 1939

In his letter dated Istanbul,  22 December 1939 No. 575g reported the German naval attaché to the Oberkommando der Wehrmacht Abteilung Ausland the steamships passing Istanbul. An item reported that the British tanker Luxor was armed with 1 gun and 1 flak at the stern.

Source

Bundesarchiv. German Marineattaché for , Greece, Romania and Bulgaria 1939-1941. RM 12-II/459.