Wellington - Two brothers convicted of murdering a 3-year-old girl who was kicked to death after months of abuse, including being hung and spun on a rotary clothesline and put into a tumble dryer, were sent to prison for a minimum of 17 and a half years Wednesday, news reports said.

Wiremu Curtis, 19, and Michael Curtis, 22, were found guilty late last year of the murder of Nia Glassie, who died from severe brain damage in August 2007, 12 days after being taken to hospital.

The girl's mother, Lisa Kuka, 35, who had been in a relationship with Wiremu Curtis, was sentenced to nine years in prison after being found guilty on two counts of manslaughter for failing to provide the necessities of life and not protecting the child from violence.

Passing sentence in the Rotorua High Court, Judge Judith Potter said Kuka had chosen to ignore the risk to which her daughter was exposed by leaving her in the brothers' care.

"Lisa Kuka was the only person Nia could look to for care, and she failed her utterly," she said.

The court was told that the girl lay in a coma for 36 hours after being kicked repeatedly in the head as her mother and other family members celebrated Michael Curtis' 21st birthday with a party.

Michael Curtis' partner, Oriwa Kemp, 18, was jailed for three years and four months and Nia's cousin, Michael Pearson, 20, for three years after being found guilty of child cruelty charges. (dpa)