Eight people from one family have been arrested across three states following a six-year investigation into suspected historical and ongoing child abuse in southern New South Wales.

Detectives from the state crime command’s child abuse and sex crimes squad established Strike Force Hermoyne in 2012 to investigate allegations of incest, child sexual assault and serious neglect of children.

Detectives this week arrested eight family members in three operations in NSW, South Australia and Western Australia.

A man and woman arrested in the Griffith area, in NSW, remain in police custody and will face the local court on Friday.

The 38-year-old woman was charged with perjury, while a 45-year-old man was charged with more than a dozen child sex offences, including six counts of sexual intercourse with a child under 10 and common assault.

Meanwhile, two women and a man were arrested in the Riverland region of South Australia.

The women, aged 50 and 34, were charged under a NSW arrest warrant for perjury while a 29-year-old man was charged with a similar offence as well as two counts of incest with a person under the age of 16 years.

They were remanded in custody to appear at Adelaide magistrates court on Friday, where detectives will apply for their extradition to NSW.

A woman and two men were also arrested in the Northam area of Western Australia.

A 51-year-old woman was charged under a NSW arrest warrant for perjury.

A 36-year-old man was charged under a NSW arrest warrant for four counts of sexual intercourse with a child under 10, two counts of indecent assault and having sexual intercourse with a child aged between 10 and 14.

A 48-year-old man was charged under a NSW arrest warrant for counts of sexual intercourse with a child under 10.

All were remanded in custody to appear at Perth magistrates court on Friday, where detectives will apply for their extradition to NSW.

