Human remains found in suitcases in New Zealand earlier this week were two as yet unidentified primary school-age children, police said on Thursday.

Detective Inspector Tofilau Faamanuia Vaaelua said the bodies were likely to have been in storage for several years and the victims are thought to have been between five and ten years old.

A homicide investigation was launched after the remains were found stashed in suitcases that were bought at an auction in the country's largest city Auckland.

The suitcases were auctioned as part of storage unit sale, and taken home by an unsuspecting family after their winning bid.

Residents at a home in South Auckland called police last Thursday after making the grisly discovery.

Police do not believe the family were involved in the suspected homicides. 

The auctioning of abandoned contents is a common practice for storage units with unpaid bills.