A 19-year-old woman was crouched naked and looking "broken" in an Auckland basement when a woman was told to use a tube to sexually violate her, the attacker has told a court.

Jaclyn Keates was last year jailed for her part in a May 2016 attack on the now 20-year-old victim.

Prosecutors say the victim was pulled off an Auckland road and subjected to a long attack in a basement before being driven to Dome Valley where she was beaten with a hammer and left for dead.

Tauranga woman Nicola Jones and Julie-Ann Torrance are standing trial for attempted murder in relation to the attack, while Wayne Blackett has pleaded guilty to the charge.

Jones, Torrance, Blackett and Michelle Blom, also face a series of charges between them, including kidnapping, sexual violation, cutting the victim's hair and assault.

On Friday, Keates told the High Court at Auckland she had smoked methamphetamine and travelled to Auckland city, near Karangahape Road, with Jones, Torrance, Blackett and Blom for a night out.

On coming across the victim they forced her into the group's car and drove to Blom's home on Great North Road house, where they began a prolonged assault on the victim.

They accused her of sleeping with one of women's partners and stealing rings from one of their daughter's gravesites.

Keates said when she first walked into the basement, the victim had been stripped naked and was crouching on her hands and knees in the middle of the room.

She looked "sad and broken", Keates said.

"Just helpless, there was all of us against her."

Shortly after Torrance asked Keates to take a plastic tube and "shove it up her a**". Keates refused but Torrance forced her to press the tube against the victims buttocks.

Keates said she was disgusted by what had been happening and left.

She told the court, she had never met the victim before the assault, did not know the other attackers well and could not even remember what the victim looked like.

The trial continues.

Source: AAP