Sibling rivalry/bullying.

Ok so another one I don't know where to post...

Anyway any one any advice on sibling rivalry or bullying. I have a 3 yr old with possible autism (awaiting diagnosis) and a nearly 10 month old. My 3 yr old is so mean to him he goes to play with toys with my oldest the oldest runs away with the toys. When the youngest climbs the furniture near the oldest the oldest will kick him in the face and kick him off the sofa. I feel like I'm forever telling the oldest off for this behaviour and it doesn't seem to sink in. In the beginning the oldest wasn't really bothered by him used to stroke his head cuddle him try feed him. He will hug him and play with him on the very rare ocassion.