Germany's national rail operator plans to deploy small drones in an attempt to catch the culprits painting its trains with graffiti every night.

Deutsche Bahn says it will begin testing out small aerial crafts equipped with helicopter-style rotors and infrared sensors capable of thermal imaging. A "pilot" remotely steers a drone over a train yard, with the small craft able to achieve a height of up to 150 metres. An operator must also analyze the pictures captured.

The agency, which estimates it spends about $10 million dealing with graffiti annually, wants to use the photos to identify offenders. Each drone would cost Deutsche Bahn approximately $80,000.

"We are going to use this technology in problem areas, where taggers are most active," a rail spokesman told Agence France-Presse.

Currently in Germany, small drones operating on private land do not need permission from air traffic controllers. Deutsche Bahn has said it will use the drones only over its own depots.

Although no official date has been announced, the spokesperson said testing will begin soon.