Four men charged over Wollongong assault

Four men have been charged over a Queen's birthday long weekend attack in Wollongong that has left a man in hospital with a fractured skull.

A 21-year-old man lost consciousness when he was punched and kicked by a group of men as he walked on Keira Street just after midnight on June 13.

Four men - aged from 18 to 21 - were charged with affray and assault causing actual bodily harm after CCTV images of five people were published on NSW Police's Facebook page on Monday.

They've all been refused bail and are due to face Wollongong Local Court on Tuesday.