Ivan from Russia pointed out this drawing which is of Finnish origin.
The Finnish soldier holds a grenade-like item, ready to throw at the tank.
Has there been a grenade used against armoured vehicles that had this form and length?

Dimitar came with an explanation that this might be one of the variations of the Finnish "Kasapanos", which was a satchel charge against AFV's and tanks. This charge existed in several forms. Other variations can be found here: http://www.jaegerplatoon.net/OTHER_AT_WEAPONS1.htm