A truck has rolled in Dunedin, trapping its driver and blocking roads.

Police said the truck crashed at the intersection of George St and Great King St North.

Traffic was down to one lane heading south into the city from Pine Hill Rd.

The two-trailer reticulated truck has taken out a steel street lamp and a mature tree.

It was carrying plaster board and has left a trail of debris scattered and broken on the road.

Motorists are asked to be patient while emergency services clear the crash.

- Additional reporting, Otago Daily Times