The girl, 17, had been walking across the Dean Street footbridge just before 6.30pm when she was confronted by three men.

The group dragged her into nearby bushes and threatened her with a knife before sexually assaulting her.

The first man is of Caucasian appearance and between 180cm and 185cm tall, with a solid build and light hair. He was wearing a dark hooded jacket, grey tracksuit pants and black lace-up shoes.

The second man is also of Caucasian appearance, between 180cm and 185cm tall, aged in his early to mid 20s, with dark mid-length hair and a slim muscular build. He was wearing a dark hooded jacket, tan-coloured jeans and maroon shoes.

The third man is also of Caucasian appearance and between 180cm and 185cm tall, aged in his mid to late 20s, with a slim build and gaunt facial features. Police have been told the man had poor oral hygiene and was wearing a pale-blue hooded jacket with white print, black jeans and camouflaged shoes.

Detectives would like to speak with anyone who was near the Dean Street footbridge between 6pm and 6.30pm on Tuesday.

Anyone with information that could help police can call Crime Stoppers on 1800 333 000.