Police in Darwin are warning motorists to look out for four cows that have been spotted wandering on busy Tiger Brennan Drive.

Watch Commander Gary Smith says a driver struck one of the cows at about 10pm yesterday, causing damage to his car.

He says the cows are a long-term problem and police have unsuccessfully tried to capture them in the past.

"I believe they've been (around) for years but for some reason they seem to be coming closer and closer to the road," he said.

"Also it's a hundred kilometres along there too, so those cows are fairly tough pieces of animal."