A 19-year-old man is seriously injured after being bashed with a plank of wood during a street brawl on the NSW Hunter region.

Police say the fight is believed to have started at the Kurri Kurri Sportsground shortly after 10pm (AEDT) on Saturday before it moved to Barton Street.

The injured man is in a serious but stable condition in John Hunter Hospital.

An 18-year-old Weston man has been arrested and charged with inflicting grievous bodily harm with intent.

He will appear in Maitland Local Court on Sunday.

Detectives have interviewed a number of people overnight who are believed to have either been involved in the brawl or were watching it.

Investigations are continuing.