Thousands of pornographic images have been dumped at a Christchurch intersection.

More than 1000 pornographic images lay strewn across a busy Christchurch intersection after falling off a truck.

A motorist was driving near the Marshland Rd and Prestons Rd intersection, in Marshland, about 2pm Tuesday when she spotted the explicit images strewn across the area.

She said thousands of images blew about an 80 metre radius from the intersection.

"It looked like it had fallen off the back of a truck, and it littered the whole intersection, you could barely see the concrete," she said.

They were blown north along Marshland Rd and along Prestons Rd.

"I suspect the council were there to clean it up as fast as possible. And actually, a few good Samaritans pulled over to help when they realised it was not suitable material."

She said several drivers were tooting their horns as they passed through the intersection. Some men stopped to pick up copies for themselves.

A police spokesman confirmed the images were in a box that fell off the back of a truck.

Despite reports that some of the images involved children, he said police determined that was not the case.

He said Christchurch City Council staff picked up the material and it would be disposed of.

Council staff were unable to provide information late Tuesday.