COPS in Austria have freed a woman that had been kept imprisoned by her own father who apparently abused her and kept her locked up in an underground dungeon for 24 years.

The woman, named as Elisabeth Fritzl, 42, is believed to have been sexually abused and beaten by her father, 73, who has not been named for legal reasons, since 1984, as he kept her hostage in an improvised dungeon in a cellar beneath his house in a village near the town of Amstetten in Lower Austria.

Police suspect that the man fathered his daughters four children, the oldest of which is 19. All of the children lived with the man and went to school while their mother was imprisoned in the cellar.

DNA tests are being conducted in order to determine whether the man is indeed the father of his own grandchildren.

According to initial reports Mrs Fritzl, who is said to be exhausted but in a stable condition and has been put under medical and psychiatric care, was kept locked up for the whole time of her ordeal.

Her father reportedly told school authorities, as well as friends and family, that his daughter had gone into hiding and left him with her children, only communicating with occasional letters.

Police freed Mrs Fritzl after an investigation prompted by one of her children, 19-year-old Kerstin, who was admitted to a local hospital with a mysterious illness.

Doctors could not determine what was causing her condition, which left her in coma for several days, and alarmed police to find her relatives. Police visited the and later searched house where Mrs Fritzl was last registered as living the home of her father where she was kept imprisoned.

Young Kerstin is now in coma and fighting for her life as doctors are still unable to discover what is causing her condition.

Mrs Fritzls three other children are in their early teens and are visiting a school in Amstetten. A school spokesman said: The children are well behaved and have always had good notes in school.

The case is reminiscent of the one Natascha Kampusch, 20, who was snatched from her way to school at the age of ten in 1998 by Wolfgang Priklopil and spent eight years in a subterranean bunker beneath his house near Vienna until she managed to free herself in August 2006.

Priklopil, a 44-year-old technician, committed suicide by jumping in front of a running train after