NANJING - A Chinese "tiger mother" had a six-month prison term upheld on Friday by a local court, which ruled that she had gone "too far" when she had beaten her foster son over unfinished homework.

Legal experts say the case has shed light on the controversial practice of physical punishment as a motivational aid in Chinese families.

The case broke in April after widely-shared pictures on the Internet showed a boy, allegedly from east China's Nanjing City, with many red-raw welts across his back suggesting intense whipping.

Police in Nanjing detained the mother, Li, who confessed to beating her 9-year-old son with a back scratcher and skipping rope for not doing his homework and telling lies.

The boy was the third child of a rural family in Anhui Province, according to local media. He had been adopted by his aunt in the hope that he could receive a better education in the city.

Li was handed a prison term in September following a medical report that declared the boy had suffered "minor injury." Li appealed the decision.

Adding to the controversy, both the boy and his biological parents have pleaded mercy for Li. The parents said Li loved their son, but had just dealt with this issue the wrong way.

During Friday's trial, Li's lawyer showed a video made by the boy, in which he said he wanted Li to return home, and for his family to be back together.

"I'm not a bad mother. I was just trying to discipline my child," Li said at the trial. She apologized for her misbehavior and pleaded not guilty.

The prosecutors defended the sentence, saying no matter how much Li might have loved her son, she had inflicted injury on the child.

The verdict was already lenient, as mitigating factors had included the boy's forgiveness, the judge told Xinhua after the trial.

The boy's biological mother said the boy was temporarily back in her custody, but she was worried about the "poor conditions" back in their rural home, and the child's future.