Police are calling for witnesses to a Wellington bar fight during which a man was stabbed in the early hours of Saturday morning.

A brawl in the Allen St Ace of Spades bar turned ugly when a man was stabbed in the abdomen.

Bar security staff managed to separate the group and provide aid to the victim.

The man was seriously injured and remains in stable condition in hospital, police said.

Police were called to the central city venue at 1.30am on Saturday and said the incident involved a small number of patrons.

They would like to speak to anyone who witnessed the stabbing, as well as anybody who may have video footage of the fight, or has information about those involved.

Police are calling on those with any information to call 105 and reference file number 251213/4525.