This is black and white film, I saw that single scene probably in early 90s, it was black and white and seemed old. There was a group of children being taken to a gas chamber, I believe, and there was an SS-man guarding them, with a dog. He let one of the children stroke the dog and smiled to the child. That's all I remember, perhaps someone could help me identify it!
Found it! I got my dad to help me, and this is an unfinished Polish film from 1963 entitled Pasażerka (the Passenger) by Andrzej Munk. Tough one. Now I can sleep...