Inscription on reverse in full is likely to be STATSFRØKONTROLLERET. Statsfrøkontrolleret means - Stat = Goverment Frø = Seed Kontrolleret = inspected and means that the seeds are guaranteed to be disease free by the government (with thanks to Danzigman for translation).
From Paul Cannon, "I am fairly sure that this is another Copenhagen seeds seal 1) KØBENHAVN.?. 2) STATSFRØKONTROLLEN around Danish crown see Euro-Plombs. The Europlombs site is in French and the inscription on the seal is particularly clear suggesting a reading of STATSFRØKONTROLLEN."