Police believe the remains had been concealed at a storage facility for years before the suitcases were purchased by an Auckland family at an auction

New Zealand police have opened a homicide investigation after the remains of two children were discovered in suitcases purchased at an Auckland auction. Photograph: Mark Baker/AP

Human remains discovered in suitcases bought at a New Zealand auction belong to two young children and are thought to have been concealed for a number of years, police say.

Police launched a homicide investigation on 12 August, after an Auckland family unsuspectingly bought the suitcases in an online auction at a storage facility. They transported their purchases home before making the discovery and contacting police. The family is not linked to the deaths, police said.

In a media conference on Thursday afternoon, DI Tofilau Faamanuia Vaaelua said a postmortem indicated the children were of primary school age – between five and 10 years old.

“The bodies were concealed in two suitcases of similar size … I believe the suitcases have been in storage for a number of years,” he said, adding that it was likely between three to four years.

The occupants of the home who discovered the remains were “understandably distressed by the discovery” and had requested privacy, Vaaelua said.

Investigations are continuing to establish when, where and how the children died.

“Our postmortem examination is yet to be completed, there are obviously challenges in regards to the bodies represented,” he said.

Vaaelua said he had reason to believe the children had relatives in the country, who may not be aware their loved ones were deceased.

He could not confirm if police had spoken to the previous owner of the storage unit, but said police were working with Interpol and overseas agencies.

“We are looking at canvassing and collecting CCTV, but given the time period we have indicated, it will be a challenge.”

There were household and personal items found with the suitcases, which police were using in their investigation to help identify the victims.

“Today’s update will be extremely upsetting for the community to hear,” Vaaelua said.

“A lot of us [police officers] are parents and we have a job to do and we’re doing our very best to conclude the inquiry and identify the victims.

“No matter how long or how many years you serve and investigate horrific cases like this, it is never any easier to do.”