Stockholm - A German woman who was extradited to Sweden on suspicion of beating two young children to death with a hammer was Wednesday formally charged with murder and attempted murder.

Prosecutor Frieda Gummesson filed the charges at the district court in Vasteras, and said the woman - a 32-year-old student - had used a hammer or similar tool to repeatedly hit the children, aged one and three, and their mother, who survived with injuries.

The attack took place March 17 in the small town of Arboga.

The motive appeared to be that the German woman refused to accept that her former partner had begun a new relationship with the mother of the children, the prosecutor said.

Evidence included lists of telephone calls, e-mails and notes from the German woman's computer as well as a map of the neighbourhood that was found in her possession.

The German woman has been held in Vasteras, 100 kilometres west of Stockholm, since she was extradited to Sweden at end of April. The trial is due to open next week. (dpa)