Charges have been dropped against a female relief teacher who was accused of grooming a 16-year-old boy for sex.

Ammy Singleton, 28, was charged with communicating to make a child amenable to sexual activity at Port Augusta last year.

But on Wednesday, the Port Augusta Magistrates Court heard the complainant no longer wanted to proceed with the charges and the case against her was dropped.

Ms Singleton was a relief teacher at several schools in Port Augusta.

But the court previously heard the allegations had nothing to do with Ms Singleton's job as a teacher.

"The [alleged victim] … a 16-year-old young male … became aware of Ms Singleton from a picture taken of her without her knowledge at the club," Ms Singleton's lawyer Andrew Fowler-Walker told the court in May.

"[The alleged victim] then obtained details of a chat room from his friends.

"In no way was he ever taught by Ms Singleton."

Earlier this year, the principals of the Port Augusta West, Augusta Park and Flinders View primary schools sent letters to parents advising them that Ms Singleton, who taught at each as a temporary relief teacher, had been charged with a child sex offence.

All the letters stated that no students at those schools were involved in the alleged offending.

Under Ms Singleton's bail conditions she was banned from engaging in any child-related work.

ABC News has contacted the Department for Education for a response.

Ms Singleton did not comment as she left court.

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