Prosecutors to appeal Borce Ristevksi's nine-year sentence for killing Kiwi wife Karen Ristevski

Prosecutors are appealing Borce Ristevksi's nine-year prison sentence for the manslaughter of his Kiwi wife, according to reports.

In March the 55-year-old Melbourne man pleaded guilty to killing Karen Ristevski, who disappeared in 2016.

Last month he received a prison sentence of nine years with a non-parole period of six years.

Kerri Judd QC, of Victoria's Director of Public Prosecutions, announced the appeal on Monday, saying the sentence and non-parole period were "manifestly inadequate", AP reports.

There was an outpouring of anger from the family of Karen and the justice presiding over the killer's case.

"Nothing was going to bring Karen back but today was about justice. We didn't get justice today, at all," said Stephen Williams, Karen's brother, after the sentencing.

Twitter users were also outraged.

"Borce Restevski could be out of jail in about five years after pleading guilty to the manslaughter of his wife, Karen. Is life cheap?" one asked.

"Surely a human life is worth more than that," another said.

Karen grew up in New Zealand before moving to Melbourne from Lower Hutt. She and Ristevski were married for 27 years.

Her disappearance in June 2016 rocked her family on both sides of the Tasman. Her body was found in Melbourne bushland eight months later.

Her husband was a suspect from early on, but maintained his innocence until March 2019 when, a day before his murder trial was due to begin, he admitted to killing his wife.

A date for Ristevksi's Court of Appeal Case has not yet been set, AP reports.