Man dies at 'unauthorised' NSW rave

A man has died at an out-of-control unauthorised rave in NSW's north that has continued despite attempts to shut it down by authorities.

Police say the man, in his 20s, was found dead in a vehicle at a private property at Newtown Boyd, near Grafton, about 2pm on Sunday.

It's estimated 2500 people will attend the event over the long weekend and police say they have asked the organisers to shut it down, but they haven't listened.

A crime scene has been established at the property and police will monitor the event overnight.