Berlin - German police discovered a truant teenager at home in bed with her boyfriend after a neighbour spotted a man climbing into her window and reported a burglary, authorities said on Wednesday.

Thinking he had witnessed a break-in, the neighbour called police, who sped towards the would-be crime scene with their siren blaring.

When officers arrived, the girl's mother told them the room belonged to her 15-year-old daughter who was at school.

Further investigation revealed the mother was wrong.

"She wasn't looking at school books, she was in bed with her boyfriend and was presumably learning something else," Frankfurt police said in a statement.