A 17-year-old boy is dead after allegedly being assaulted at a party southeast of Melbourne.

Police said the teenager died in hospital on Saturday nearly three weeks after the assault at the Tooradin party on March 21.

It is believed a group of men became involved in an incident with the teen from Cranbourne North and the situation escalated into a physical fight.

The investigation is continuing and anyone with information about the incident on Station Road is asked to contact Crime Stoppers.