Young children riding in trailer at 100kmh

File photo / NZ Herald

A motorist near Bulls couldn't believe his eyes when he noticed young children riding on a trailer being towed by a car travelling at more than 100 km/h.

The incident happened on Tuesday afternoon on SH3 a few kilometres north of Bulls.

The father of the motorist, neither of whom wanted to be identified, said his son called *555 to alert police.

He said his son was driving north when he was passed by the car and towing a tarpaulin-covered trailer. He got the shock of his life when the tarpaulin flapped open to reveal at least three children in the trailer.

The vehicle then headed toward Marton before police stopped it.

It turned out that 10 children were riding in the trailer.

"My son was driving at the open road speed (100 km/h) so this vehicle was obviously going faster than he was," the father said.

"There was tarpaulin over the trailer, but a little further up the highway three heads popped out from under it. My son just couldn't believe what he was seeing.

There were two adults in the vehicle.

"Their actions just beggar belief. It's impossible to find words to describe their actions," the father said.

He said Marton police later contacted his son to tell him the driver of the car had been apprehended and would be dealt with.