Nearly 50 cars have been stolen or broken into across Blenheim in one month, South Island police say.

Sergeant Andrew Young urges the Blenheim public to take extra precautions to protect their cars from theft as numerous car owners in the district have been victims of crime.

From mid-March until early April, 47 cars have been either broken into or interfered with.

The 47 cars were either stolen or broken into within a month.

Young understood many of the stolen cars were used to commit further crimes in the region.

Police say the most commonly stolen cars have included older Nissan, Mazda, Toyota and Honda hatchbacks and sedans and most were parked outside homes.

Five youths in Blenheim were arrested last month after a string of car thefts across Marlborough. Photo / Patrik Stedrak

Young recommended installing a car alarm or immobiliser and keeping any valuables inside the car out of sight.

“If possible, park your vehicle in a garage or driveway, but if you have to park on the road try to park in a well-lit area,” said Young.

Five Blenheim youths were last month weretaken into custody after car-related offences across the upper South Island.

The youths were taken into custody in Springlands, Blenheim after police tracked one of the stolen vehicles that had been abandoned.

Detective Sergeant Lindsay Tilbury said the offenders have been referred to local youth services and police will continue to work with the families involved.