A German mother accused of killing nine newborn babies over a period of a decade told investigators she had been alone and too drunk to remember giving birth, prosecutors said yesterday.

The deaths of the babies between 1988 and 1999 has been described as post-war Germany's worst series of child killings and has sparked shock and disbelief that the crime went undetected for so long.

The 39-year-old woman, identified as Sabine H. from the eastern city of Frankfurt an den Oder, told investigators all the babies were hers but could not give any precise information on the manner in which they were born and died.

"The accused woman admitted giving birth to the children but she gave only very vague indications regarding the circumstances of how the children were killed," Frankfurt an der Oder prosecutor Anette Bargenda told a news conference.

She remembered giving birth to the first two children and recalled disposing of the second child in a balcony flowerpot but could give only hazy accounts of the others.

"Regarding the dead children three to nine, she said she couldn't remember how the killings took place because when the birth contractions began she had drunk a considerable amount of alcohol," Dr Bargenda said.

Police discovered babies' bones buried in sand and earth in flowerpots on Sunday in a village in the eastern state of Brandenburg, after a man who had been clearing a garage there found human bones stored in a fish tank.

Authorities arrested Sabine H. a day later on suspicion of killing the children between 1988 and 1999. Officials had previously said the killings had extended to 2004.

A spokesman said prosecutors had withheld some details of her statement as the investigation was continuing.

"It's devastating occurrence for our city," said Martin Patzelt, mayor of Frankfurt an der Oder.

Dr Bargenda said Sabine H., who has three adult children aged between 18 and 20 and an 18-month-old child with a new partner, had told officers she had given birth alone and had never visited doctors during her pregnancies.

She said her husband had spent long periods away because they had marital difficulties and did not notice her condition.

"The first child was wanted, the second so-so and the third child was too much for her," Dr Bargenda said, adding that the woman appeared to be relieved the case had come to light.

Sabine H. kept belongings at the site where the remains were found in the town of Brieskow-Finkenheerd, some 80 kilometres southeast of Berlin near the Polish border.

Dr Bargenda said the suspect had told police she was happy to sit on her balcony, where she first kept the flowerpots, because she felt close to her children.

Her motive for the killings is still unclear. Prosecutors said psychiatric assessments still had to be made.

Police said Sabine H. first came to their attention last month after they arrived at her flat to break up a noisy argument with her partner and noticed she was drunk and her toddler in a bedraggled condition.

They then alerted social services and were in the process of charging her with negligence at the time of the discovery.

Police officers are still searching other sites connected to Sabine H. but have not found any further remains. Investigators are awaiting autopsy results to determine the cause of death.