THREE masked assailants attacked a Clyde man who sustained serious head injuries and is being treated in hospital.

Staff at The Alfred hospital said the man was in a stable condition after being hit with a blunt weapon.

Three men forced their way into the Ballarto Road residence of the victim, possibly through a door, about 11.15am Saturday 10 January. They demanded money from the 59-year-old man and his family before assaulting him and his 24-year-old daughter.

Detective Senior Constable Paul Topham from the Armed Crime Taskforce said the offenders struck the man with a hammer, and knocked him unconscious.

The man was airlifted to The Alfred hospital with critical head injuries. His daughter received a minor head injury, but did not require hospital treatment.

Police are appealing for anyone with information or witnesses to the attack to contact Crime Stoppers on 1800 333 000.