An 18-year-old girl escaped from a German prison by hiding inside the suitcase of an inmate friend when she was released.

According to prison authorities, Steffi Krause escaped from the youth prison in Neustadt am Ruebenberge when her 19-year-old accomplice was released.

Krause's escape was only discovered in the evening by prison wardens when she was found missing from her cell.

A prison spokesman said they surmise Krause escape by hiding in a suitcase as the wardens reported they have noticed "that the suitcase was unusually heavy" of the 19-year-old inmate when she officially check out from the prison.

Police are still tracking down the two teenagers.