In this March 20, 2018 file photo shows the prison of Vechta, Germany. AP

Prison authorities in the northwestern town of Vechta told news agency dpa the 18-year-old scaled a 4-metre wall last week to get to his ex's window.

Prison officials intercepted the man. He refused to climb back down, and the fire service was called to bring him down with a ladder.

It wasn't clear whether the escapade succeeded in winning back the heart of the young woman, also 18, who had broken up with him by phone. The man is being investigated for trespassing and unauthorised contact with prisoners.

Regional broadcaster NDR reported that the man was half-naked, having taken off many of his clothes to avoid getting caught on barbed wire.

Associated Press