Christchurch Police are investigating an assault that left man with a fractured skull.

The 26-year-old Auckland man, who has gang connections, was visiting Christchurch when he was attacked on Wednesday night around 9pm.

He was taken to Christchurch hospital and treated for multiple head injuries but has since been released.

Police have since interviewed the man, and his two friends who were with him at the time of the attack, but are also appealing for information from anyone who may have witnessed the attack.