A man is in a critical but stable condition in the Royal Hobart Hospital after being assaulted at Arthur River on Tasmania's north-west coast.

Police said the 47-year-old suffered serious head injuries during the attack early on Saturday morning.

He is being treated in Hobart after being transferred from Burnie.

Police have spoken to several locals and said it was an unusual incident for the town, which has a population of around 120 people.