A 31-year-old man has died at Maude, near Hay, in southwestern NSW, after he fell off the back of a ute.

Police say the man was seen getting into the back section of the vehicle with several others, outside a pub at Maude, about 12.20am today.

As the ute driver tried to turn from Maude Road into Nap Nap Road, some of the passengers travelling in the rear were apparently thrown onto the roadway.

The dead man, from Rochester in Victoria, struck his head on the road, suffering critical injuries.

Police say the driver of the vehicle and remaining passengers picked up cartons of alcohol which had fallen from the ute, placed them back in the rear, then drove off, leaving the injured man lying on the road.

A short time later, people travelling in another vehicle went to his assistance, however emergency services workers were unable to revive him.

Police want to question a group of people who were travelling in a white 2004-'06 Toyota 75 series Landcruiser ute, at the time of the man's death.

The vehicle has a single cab, with dog cages on the rear tray and a spotlight on the roof.

It is believed to have Victorian registration plates, QMK-277.

It might be travelling to, or within, Victoria.

Anyone with information about the vehicle is urged to contact Crime Stoppers on 1800 333 000.

The 31-year-old man's death followed a single car accident late last night at Old Bonalbo in the state's north.

A 53-year-old local man died after his car crashed into a tree.