Nov 26 (Reuters) - A South Korean-born New Zealand woman was sentenced to life in prison on Wednesday for murdering her two young children, whose bodies were discovered in suitcases in an abandoned storage locker more than three years ago, New Zealand media reported.

Hakyung Lee was convicted in September after admitting to killing the children, aged eight and six in 2018, the year after the children's father had died of cancer.

Lee pleaded not guilty by reason of insanity and represented herself during the trial, supported by two lawyers.

Lee's lawyers on Wednesday argued that a life sentence would be unjust given her mental health issues, but prosecutors said there was no evidence Lee was suicidal at the time of the killings, the New Zealand Herald newspaper reported.

Judge Geoffrey Venning rejected calls for a lesser penalty, though he approved compulsory treatment at a secure psychiatric facility, with the condition that Lee will return to prison once deemed mentally fit, the report said.

"You knew your actions were morally wrong ... perhaps you could not bear to have your children around you as a constant reminder of your previous happy life," Venning said.

Lee must serve a minimum non-parole period of 17 years.

Life imprisonment is the harshest punishment available in New Zealand, which abolished the death penalty in 1989.

The court, during the trial, had heard that Lee gave the children an overdose of prescription medicine in 2018, before wrapping their bodies in plastic bags and putting them in the suitcases.

The children's remains were discovered in 2022 by a family sorting through the contents of a storage locker they had bought at an online auction.

New Zealand police launched a murder investigation and Lee, who had moved to South Korea in 2018, was extradited to face trial in November 2022.

(Reporting by Renju Jose in Sydney; Editing by Lincoln Feast.)

((renju.jose@thomsonreuters.com;))