Police are investigating a suspected fatal assault after a man was found on Tweed Heads Street

Police are investigating the death of a man who was believed to have been attacked and left outside a home on the New South Wales north coast.

Emergency services attended William Street, Tweed Heads South, at around 3am on Sunday to reports of an assault.

Paramedics began treating a man they found lying on the ground in front of the house, but he died at the scene.

The man, believed to be in his 30s, has not yet been formally identified.

A crime scene has been established and police are investigating.