Elisabeth Fritzl has spoken for the first time about the horrors she and her children were forced to endure while imprisoned by their father in a cellar under the family home in Austria.

The 42-year-old was kept prisoner by Josef Fritzl for almost a quarter of a century, during which time she bore him seven children.

Finally freed from her dungeon in April, Elisabeth has told the judge investigating the case that she was raped up to three times a week by her father and if she tried to resist, her children suffered.

She also alleged that Mr Fritzl threatened to leave her and the children to die in the cellar if they did not follow his commands.

"He was very brutal against me," Elisabeth told judge Andrea Humer in an interview, extracts from which were published in The Sun. "And when I did not agree to have sex, then the kids would suffer. We knew he would kick us or be bad to us."

Elisabeth, her eldest daughter, 19, and two sons now aged 18 and 6, were imprisoned in a concrete bunker underneath the Fritzl family home in Amstetten. Her three other children, two girls now aged 16 and 14 and a boy now aged 12, were chosen by the retired electricial engineer to live upstairs with him and his wife.

Another baby boy she gave birth to in the cellar died soon after being born and was allegedly thrown into a domestic furnace. Prosecutors in Austria hope to charge Mr Fritzl with manslaughter over that death.

The six survivors were only freed after the eldest daughter, Kerstin, collapsed on April 19. She was rushed to hospital after Elisabeth pleaded with her father to let her daughter see a doctor.

In her interview with Ms Humer, Austria's top female judge, Elisabeth said that her father threatened to leave them to rot in the cellar, which had no windows and was sealed by an electronically-locked door.

"He said he could close the door whenever he wanted and then we would soon see how we survived," she said.

The judge asked: "Did you take these threats as real?" Elisabeth replied: "Yes."

Elisabeth also told of how she tried to keep life as normal as possible for her children when their father was not around.

"When he went away we led our own lives," she said. "When he was here it was all silence. He was just all-powerful.

"It was his kind of communication to use rough words. He would be insulting against me and the children.When he was at the table and we were eating and someone was holding their knife wrongly, or did not want to eat, there would be verbal abuse.

"He wouldn't let the kids develop their own personalities. He would not allow the kids to have their own will."

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