Detectives from Harbourside Local Area Command have released CCTV images of two men and two females they believe may be able to assist with their investigation into a glassing on Sydney’s North Shore.

Between 2-2.15am on Sunday 29 July 2012, a 20-year-old man was walking across the dance-floor in a hotel on Willoughby Road at Crows Nest, when he was spoken to by a man and woman.

As the 20-year-old went to walk away a glass was thrown at his face knocking out a tooth and cutting his upper lip.

Hotel staff rendered first aid to the injured man and police were alerted.

Officers from Harbourside Local Area Command are investigating and would like to speak to four people seen on CCTV footage who may be able to assist with their inquiries.

The first person is described as being a female of Caucasian appearance, about 25-30 years of age, with long dark hair, medium to slim build, wearing a brown singlet top, blue or light grey jeans and white shoes.

The second person is described as being a male of Caucasian appearance, about 25-30 years of age, with short dark brown hair, medium to solid build, wearing a grey and green chequered collared long sleeve shirt and blue jeans.

The third person is described as being a male of Caucasian appearance, about 25-30 years of age, with short sandy hair, full beard medium build, wearing a blue and grey chequered long sleeve collard shirt.

The fourth person is described as being a female of Caucasian appearance, about 30-35 years of age, with long dark hair, medium to large build, wearing a white long sleeve top, and carrying a dark coloured overcoat.

Any witnesses who have not yet been spoken to by investigators or anyone with information are asked to contact police.