The first plates of the Milizia Nazionale Forestale were issued after January the 1st, 1935: they were
white with the letters M.N.F. in red followed by a black serial number, as you can see in the picture on the left.
Afterwards since the end of 1935, the plates used by the Milizia Nazionale Forestale in Africa had a minor change, with the addiction of the letters A.O. placed on te left of the number: they were 6x3 cm. on the rear plates and 3x1 cm. on the front.
Many thanks to Ernesto Vitetti for the first picture and to Duccio Baldassini for the second one.