British steamship Lassell arrived with Polish aircraft on board according to a letter of the German naval attaché dated 26 September 1939

In his letter dated Istanbul, Turkey 26 September 1939 No. 60g.Kdos reported the German naval attaché to the Oberkommando der Kriegsmarine at Berlin the British steamship Lassell was still lying in the harbour. It became clear that she was loaded with aircraft originally destined for Poland. It was unknown if Turkey took over the aircraft. While the ships was still lying here indicated that negotiations were going on. Nothing could be said over preparations for unloading the cargo.

Source

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