A robot has killed a contractor at one of Volkswagen's production plants in Germany, the car manufacturer says.

The man died on Monday at the plant in Baunatal, about 100km north of Frankfurt, VW spokesman Heiko Hillwig said.

The 22-year-old was part of a team setting up the stationary robot when it struck and crushed him against a metal plate.

Hillwig said initial conclusions indicate that human error was to blame, rather than a problem with the robot, which can be programmed to perform various tasks in the assembly process.

He said it normally operates within a confined area at the plant, grabbing car parts and manipulating them.

Another contractor was present when the incident occurred, but wasn't harmed, Hillwig said.

Hillwig declined to give any more details, citing an ongoing investigation.

The Financial Times said the worker was hit in the chest by the machinery and pressed against a metal plate while standing inside the safety cage that contains the automated equipment.

It said prosecutors were investigating.