A woman has told a north Queensland court she was sexually assaulted by a foster teen who lived with her family in 2006.

Three Queensland sisters are suing the state government after they were abused by a rapist foster child placed in their home.

The sisters, aged 17, 16 and 14 at the time of the abuse, allege the Child Safety Department put them at risk as the 14-year-old boy was a known sex offender.

The boy moved in with the sisters and their mother in December 2005, two years after being convicted of raping a three-year-old girl at the home of previous carer.

The eldest sister, who can’t be named, told Cairns District Court on Tuesday that before the boy moved into their home a department officer visited the family.

She alleges the officer told the family the boy’s previous carer had likely exaggerated the allegations.

“They didn’t tell us that he had raped,” the eldest sister, who sobbed throughout her court appearance, said.

She says the officer told the family they would be safe.

If she had known the teen was accused of raping the toddler she would have moved in with her grandmother, she says.

She told the court she was sexually abused by the foster child on numerous occasions in 2006.

“I was ashamed, but also [felt] dirty and guilty,” she said.

When she confronted her mother some time later her mother told her not to go to the police because she feared the boy would be molested if he went to jail.

The sister told State of Queensland barrister Dan Kelly she didn’t go to police herself because her mother told her the department was “taking care of it”.

Mr Kelly also questioned the sister over why she didn’t move out of the house and why she didn’t hide a spare key, which the boy used to gain access to her room.

“I don’t remember,” she said.

“I don’t know.”

She says the teen never threatened her with violence and didn’t tell her not to tell anyone about the alleged abuse.

The trial continues.