Marlborough Police are calling for a ''stupid'' nail thrower to stop before someone gets seriously injured.

Someone has twice thrown nails onto State Highway 1 north of Blenheim this summer.

Sergeant Barrie Greenall says at least 20 tyres were punctured on different vehicles on January 1 and 11 because of the nails.

However, he says the person could be charged with manslaughter if the nails cause a fatal crash.

"It is mindless, it is stupid, and it is inherently dangerous, I fail to see why somebody would get gratification from doing this."