Suzuka Hatakeyama, 35, fell to her knees on the courtroom floor to apologise to the boy's parents after the judge handed her the life term, but spared her the death penalty.

'I am sorry for depriving you of your precious child,' she told the parents, who wanted her to be hanged.

The court ruled that Hatakeyama killed her daughter, Ayaka, in April 2006 by flinging her from a bridge into a river in the northern Akita prefecture.

After her daughter's body was found, Hatakeyama drew national sympathy as a single mother who had lost her only child.

She had demanded a police investigation and put up handmade posters seeking witnesses to find out who killed her daughter.

But it was later found out that she had killed not only her daughter but also Goken Yoneyama, a seven-year-old in the neighbourhood, more than a month after her daughter's death.

She had invited the boy into her house as he was walking home from school, and strangled him with a rope before dumping his body along a river. Prosecutors said she had planned the murder to avert suspicions that she had killed her daughter.

She confessed to killing both children, but her lawyers argued that she was not mentally competent. The defence counsel immediately appealed to a higher court.

Hatakeyama earlier wrote an open letter of apology to the dead boy, saying: 'It must have been scary and painful. I'm sorry that you couldn't make it home.'

But she wrote in a diary while in detention that she felt 'little guilt' over his murder.

'I also don't understand why his parents are so furious. They have two more kids,' she wrote in the diary, parts of which were leaked to the media.

Judge Toshiro Fujii rejected prosecution calls for the death penalty, saying he took into consideration her mental state and the fact that her murder of the boy was not premeditated.

Her former boyfriend testified in court last year that Hatakeyama considered Ayaka a nuisance and shut her daughter out of the house when he was with her.

AGENCE FRANCE-PRESSE