A South Korean court has sentenced a teacher to life in prison for fatally stabbing an eight-year-old girl, in a case that shocked the nation.

Myeong Jae-wan, 48, killed Kim Hae-neul, after luring her into a classroom in the central city of Daejeon in February.

Prosecutors had sought the death penalty for Myeong, saying that the victim's family had asked for a harsh punishment.

But the court said that while "the risk of reoffending is high, it is difficult to conclude" that Myeong must be executed.

Myeong said that she would reflect on her mistakes for the rest of her life.

She said her judgement had weakened at the time of the stabbing as she was receiving mental health treatment.

Prosecutors said Myeong showed no remorse while the case was being investigated. However, Myeong submitted dozens of letters to the court expressing remorse.

Myeong had previously requested a six-month leave of absence, citing depression, but returned to school in 20 days, after a doctor assessed her as being fit to work, the Daejeon education office said in February.

She had displayed violent behaviour in the days before the stabbing, including putting another teacher in a headlock, the education office said.

On the morning of the stabbing, two education officials had visited the school to investigate that earlier altercation.

Myeong told police that she had bought a weapon on the day of the attack and brought it to school, planning to kill herself along with a random child.

She also told the police that she had lured Kim into the media room before attacking her.

Kim, the student, student was reported missing after a bus driver informed the school that she had not arrived to be picked up that day. She was found in school later that day with stab wounds, along with Myeong.

Myeong also had a wound on her neck, which police said might have been self-inflicted. It was stitched up later in hospital.

South Korea's leaders at the time called for safety measures to ensure such incidents never happen again.

Myeong has also been ordered to wear an electronic location tracking device for 30 years.

"As an elementary school teacher, the accused was in a position to protect the victim," said the court's verdict on Monday. "But she committed this brutal crime in which a child was not protected where they should be most safe."