A mother who dumped four of her babies in buckets filled with concrete that she then kept in her apartment for two decades was arrested in Japan on Tuesday.

Mayumi Saito, 53, told investigators she had given birth to the infants between 1992 and 1997, a police spokesman told AFP.

Saito handed herself in at an Osaka police station on Monday and confessed, saying she did not think her desperate financial predicament made it possible for her to look after the children, local media reported.

Detectives who searched her home found four concrete-filled buckets in a closet.

Scans indicate that each one contains what appears to be the remains of an infant, the Asahi Shimbun reported.

Police are still interviewing the woman, who lives with her son, and trying to determine whether she killed the babies or whether they were stillborn, the report said.

"I did not think I could afford to raise them. I had no one to talk to," she told police, according to national broadcaster NHK.

It is unclear why she turned herself in now, local media said.

Saito came forward three weeks after police arrested Takahiro Shiraishi, 27, dubbed the "Twitter killer", who has confessed to killing and dismembering nine people he met via social media.

Investigators found him in his apartment just outside Tokyo surrounded by the festering remains of his victims inside coolers and containers.