Konga.

Dr. Decker returns from Africa after a year, presumed dead. In that year, he discovered a way of growing plants and animals to an enormous size. He brings back a baby chimpanzee to test out his theory. As he has many enemies at home, he decides to use his chimp, 'Konga', to 'get rid of them'. Then Konga grows to gigantic proportions and wreaks havoc all over London!