A South African woman faces judgement Thursday on charges of kidnapping a newborn baby and raising her for 17 years before an astonishing coincidence reunited the girl with her family.

The accused woman pleaded not guilty, saying she had been handed the baby at a train station after entering into a private "adoption" programme.

The girl's real identity came to light in February last year, when her younger biological sister began attending high school and pupils pointed out her remarkable likeness to a final-year student.

The younger girl told her parents, who met the older girl and immediately believed she was their long-lost baby.

They called the police, and DNA tests confirmed that the girl was indeed their child, whom they had named Zephany Joy Nurse.

Without knowing it, the Nurse family had been living within a couple of kilometres (miles) of their kidnapped daughter, while celebrating her birthday every year and never giving up hope of finding her.

The 50-year-old accused woman cannot be named to protect the new identity of the kidnapped girl, who requested protection from international media interest.

The girl's mother, Celeste Nurse, 36, wept as she described in court how she woke up in the maternity ward of a Cape Town hospital to find her three-day-old baby had vanished from her cot on March 30, 1997.

Witnesses said they had seen an unknown woman in a nurse's uniform at the hospital around the time of the kidnap, and one of them picked out the accused at an identity parade.

The accused woman also sobbed in court as she told of being barred from seeing the girl after her arrest in February last year.

She told the court that after a miscarriage in December 1996 she paid a woman who promised to find her a child to adopt.

In April 1997 she was handed a baby wrapped in a blanket at a train station in Cape Town, she said.

She had not told her husband of her miscarriage, so presented the baby to him as their own child, she said.

She faces a minimum of five years in jail if convicted of kidnapping.