A farmer on a quad bike helped "herd" a motorist who fled into a cow paddock after crashing his car.

In a clip shown on TVNZ's Highway Cops, police find a set of skidmarks on a gravel road in rural Canterbury which lead to the paddock.

The driver is standing in the middle of field, and Constable Ben Grant chases him on the back of the quad bike.

A bizarre chase followed, in which the man slowly jogs away while the farmer and cop circle him. He then leaps a fence, evading police who keep their distance out of concern that he might have a knife.

Another farmer watches on in bemusement from his tractor.

"He's lost the plot, I think," says the farmer, named only as Scott.

"Stressing out, I don't know. He's obviously had a prang down here.

"He's on something, I think, by the look of it."

Police said they suspected the motorist had been under the influence of drugs and alcohol.

Meanwhile, a passenger in the crashed car claimed not to know anything about the incident.

He said he was asleep - despite evidence the car had done several burnouts before crashing beside the field.

The driver was eventually stopped in its tracks - with the help of police dogs.

"Only in New Zealand," said one commenter on Facebook.