The animal was tied up outside a Co-op store in School Road, Tilehurst, Reading, at about 1030 BST on 17 April when the girl tried to stroke it.

The dog, thought to be a Staffordshire Bull Terrier, then bit the girl cutting her neck, cheek and under her nose.

Police are trying to trace a woman in her 50s with shoulder-length ash blonde hair who was with the dog at the time.

She is thought to be the owner of the dog, which was white with a black patch over one eye.

Police are worried the dog could bite again and are appealing for witnesses and urging parents to teach their children the potential dangers of dogs.