Finnish police have found five badly decomposed human foetuses in the storage room of an apartment building in the northern town of Oulu.

A female resident has been arrested on suspicion of manslaughter, authorities said this afternoon.

Police checking the contents of packages found in the cellar by maintenance workers yesterday were approached by a 35-year-old woman who told them they contained the remains of stillborn babies to which she had given birth at her home five to ten years ago.

Detective Inspector Seppo Leinonen said police arrested the woman, who is married with children.

"We are investigating the case as a homicide as the foetuses are so close to full term that under normal conditions they would have been viable to survive," Mr Leinonen said.

He said police believed the corpses of the nearly full-term foetuses could be several years old.

Mr Leinonen would not give further information about the woman or comment on the number or ages of her living children.

Her family moved into the building only a few months ago, and police suspect she brought the bodies from her previous residence.

A maintenance company had alerted the police after locating packages emitting a foul odour in the cellar at her apartment building in Oulu, a city of 200,000 people that was once a key Nokia research and development site.

Mr Leinonen said there was no reason to believe anyone besides the woman knew of the hidden bodies.

Some of the bodies were badly decomposed, complicating the investigation, he added.

"The woman has not been able to give any intelligible reason for her actions," Mr Leinonen said.