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New York City authorities are dropping sexual assault charges against five teenagers after their accuser recanted her story.

The woman initially told police she was gang raped at gunpoint in a Brooklyn park on 7 January.

Police arrested five teens, but parts of the woman's story began to come under scrutiny as more details emerged.

Her father was said to have been chased off by the suspects, but it took him nearly 30 minutes to alert police.

The teenagers said the encounter was consensual. They told police when they entered the park they saw the woman and her father engaged in a sex act.

Prosecutor Kenneth Thompson said the 18-year-old woman provided "multiple inconsistent accounts" when detectives questioned her.

"That night, this young woman's father and the five young men engaged in conduct that was reprehensible and wrong, but because of the lack of reliable evidence, criminal charges simply cannot be sustained," Mr Thompson said.